Stating how truly amazing I think this game is would still be an understatement...

User Rating: 9.5 | The Elder Scrolls IV: Oblivion - Game of the Year Edition X360
*This will probably be my longest review ever as I am going to try and do this massive game justice.

Setting:
Elderscrolls IV: Oblivion is set in the province of Cyrodiil, the heartland of Tamriel. The era in which this game takes place would most closely relate to what we consider to be the "medieval" times. Stone, wood, iron, open fields, lakes, forests, animals, town guards and citizens aplenty!

Intro:
I honestly do not even know where to begin with this title, so I'll start with what made me buy it.
Before I even owned a 'next-gen' console, I was still having that internal struggle that everyone always has when deciding between the PS3 and Xbox 360. This was around 2006, I believe. I was really unsure until I overheard a conversation among some employees of a local gaming store; They were talking about how vast and massive this game called "Oblivion" was. It was the first I'd heard about it so I didn't think too much of it. Later that week, a few friends of mine at work were talking about what an excellent game it was and how different each of their stories were unfolding.
By this time, I was intrigued enough to actually research it. Low and behold, it was only available on the Xbox 360 (at the time). So, being a game that I was highly interested in, I purchased it, the console, and the two pound strategy guide.
300+ game play hours later, here we are. I still do not regret my decision and I do not feel that a single minute spent playing this game has been a waste.

Main Menu:
Very clean. Theme is set to look like the map you receive inside the box containing the game. Easy to use. Not much to it. Amazing musical score. My only problem with it is the extended time you will suffer when "loading extra content" every time you access the main menu (which comes from DLC).

Opening Cut Scene:
Any game that opens with Patrick Stewart's voice is an automatic win, in my opinion. You also get a nice little fly through of Cyrodiil as well. After that, it leads into the monumental game that could easily consume the rest of your natural life.

First Impression:
After completing the training portion of the game and emerging into the actual world, I was absolutely astonished; Blown away.
Open land as far as the eye could see, trailing off of a shimmering lake.
Mountains, ruined stone fixtures, and a vivid sky; All in the same view.
This is what really completed the entire package for me. I was hooked from then on.

Graphics:
At the time, this was the first next-generation game I had played aside from Fight Night Round 3, so, needless to say, I was impressed. This game delivered in every aspect. Lighting, shading, character models, everything. The detail is spot on; Whether you're shopping in a city, horseback riding through a forest, or discovering the secrets buried deep within an Ayleid ruin, you will want to stop and inspect every bit of what you're seeing. No matter how many quests you complete, or how many rare items you obtain, there is no greater reward than stopping to take in the marvelous sights this game has to offer.
Even to this day, with an outdated engine running it, I would still argue that it is one of the best looking titles available.

Physics:
The physics engine could use some work, but it still delivers a good, solid configuration, especially for the time in which it was released. Most things in the game tend to react as they would in real life when you interact with them (minus candles, for example). However, I have noticed a few bugs here and there while playing, but nothing that would take anything away from how good this game is. Some things, for example, will seem rubberized (i.e. pushing or pulling people) instead of seeming like they carry 'real' weight, or some things might simply spas out of control for a few seconds (i.e. if you shoot an explosive fireball at something hanging from the ceiling by a chain, or get a body stuck inside of a closed gate). The physics are on point for the most part, though.

Controls:
The default controls are simple and easy to pick up. If, for some reason, they don't feel natural, you can customize them to your liking.
The game can be played from first or third person at any point in the game and they make it easy to do either. Changing from one point of view to another is fluid and effortless; It shouldn't throw you off at all. I'd say the hardest part about the controls are getting used to navigating the menus (maps, items, spells, etc). Once you have mastered that, it's butter.
Combat is easy and free flowing and maneuvering around obstacles is cake. I really have no issues with Oblivion's control system.

Artificial Intelligence:
The A.I. in the game is simple and effective. Once you figure out what type of character you're dealing with (i.e. magic user, warrior, crazy person, rational citizen, monster), it's easy to assume what they're going to do in certain situations. This is not necessarily a bad thing. I can assure you that the A.I. is not dumb. Sometimes being led around by a non-playable character can be a little slow and drawn out, but for the most part, I like the A.I. system. Guards, people, creatures, and enemies usually react the way they should depending on your actions.

Difficulty:
Oblivion's difficulty can be changed in-game at any time. It defaults to about half way, which I'd say is fitting. Slide the bar to the far left, and you'll be cutting virtually everything down with one shot at any level. Slide it all the way to the right and, well, you'll be sliding it back to the left shortly after.
Aside from that, the game offers some decent challenges, tough puzzles, and too many quests to count. I challenge you to find every discoverable location in this game.

Storyline & Plot:
Oblivion has one of the coolest, most epic (main) storylines out there. I won't reveal any spoilers, but I will say this: It gets pretty intense.
Aside from the main quest though, it offers so many side quests they'll be spilling out of your quest log within the first 10 hours of game play. These side quests will lead to character development, sub plots, back-stories, alternate side quests, moral challenges, factions, guilds, friendships, enemies, new areas, items and much, much more. (Sorry for sounding like the back of the box, but it's all true!)

Voice Acting:
The voice acting in this game is arguably one of it's most amazing features as it contains over 1000 non-playable characters speaking over 60,000 lines of unique dialogue! They hired top notch voice actors who are truly talented and I hope they continue to work with Bethesda in the years to come. They really delivered in this aspect of the game and made it believable.
My only issue was that after you play for so long, (100 hours or more) you'll start to become familiar with the actors voices; So familiar, in fact, that you'll be able to tell which people did the voices for each character in the game. I'd like to see a bigger cast of voice actors in later games to combat that.

Sound, Music & Ambiance:
The music in Oblivion is absolutely fitting for the type of game that it is; Epic and meaningful. Deep string orchestral scores really hit home here. The music can change from heartfelt to bizarre and frightening depending on the situation. For example, it recognizes when you're in battle and adjusts to a more intense score, but when you're just out and about exploring, it will be a calm and light ensemble.
The audible atmosphere in this game is one to be rivaled with. For example, you can hear the wind blowing, rain hitting a wooden roof, thunder, foot steps, horse hooves, swords clashing in the distance, people talking, things dropping, spells being cast, drinks being drank, and food being eaten; All at the same time. It doesn't seem cluttered with noise when this is all going on either. It's delivered flush and smoothly to the ear.

Game Development & Delivery:
This game develops as fast and as smooth as you let it. If you want to take a slow, focused approach, that is perfectly fine. If you like to run through games in a barbaric fashion, it's possible. The delivery is what you make it. It's truly a unique experience no matter who you are or how you play.

Unique Features:
There's a unique feature in Oblivion that I would really like to see incorporated into other RPGs. This feature being the ability to precisely and accurately customize your character's class. At the beginning of the game, after you pick your race and design their looks, you can define your person's specialties, specific skill sets, primary abilities, secondary abilities, main attributes, strengths, and you can even pick the set of stars they were born under! Then, not only can you name your character, but you can also name the class you made for them! I hate, as a creative person, being limited to pre-designed, inadequate templates. No freedom to really find your niche in a game with those kinds of limitations.
Another unique feature to Oblivion is the sheer amount of free roaming available to the player. You can literally walk as far as the eye can see. (Until you hit those awful invisible borders.) It offers roughly 16 square miles of land, not including dungeons and other things below sea level.
The last major feature I like about Oblivion is the ability to create a truly custom spell. I wasn't really sold on the whole idea until I created a spell that physically paralyzed a person for 8 seconds while simultaneously catching them on fire; They burned alive; Next to a lake. Afterward, I scavenged a 'Potion of Fire Shield' from their body.
There are so many other notable features specific to this game, I honestly cannot cover them all if I tried, so I'll leave it at my favorite three.

Ending (No Spoilers):
By the time I had gotten around to actually completing the main quest, I was quite impressed with the way it turned out. You can complete the main storyline right off the bat or you can wait until you feel like getting around to it, either way, you're not going to lose any content anywhere else in the game. Everything is always available at any time, no matter which order you decide to do it.

Replay Value:
This game doesn't really need a 'replay value' as it will offer so much content you probably will not be able to complete it all with a single character anyway. It does, for the sake of argument, offer a good replay value in the aspect that you can always start a new character, with a new race, and a new class and play through again making different decisions than you did previous times around; Or, most likely, you'll discover new quests or find new locations during your following play throughs.

Multiplayer/Online Features:
There is no multiplayer. There is no form of online play. Unless you consider earning trophies/achievements a form of 'online' play. I would like to see this franchise go mass multiplayer though; Could possibly be a WoW killer.

Strengths:
Oblivion shines brightest in the respect that it delivers a massive amount of content with relative ease; It doesn't seem forced and is enjoyable from start to (whatever you would consider) finish. It has solid graphics, great voice acting, fluid controls, and an epic storyline paired with the perfect setting.

Weaknesses:
If you're not a fan of cave crawling, looting, treasure hunting, level building, or things of that sort, then Oblivion would surely get repetitive after playing for so long. Aside from that, I'd like to see some form of multiplayer or at the very least, a leader board of some sort in the future titles.

Summary:
To summarize everything I've covered, which I know is a lot, I can only say that I have only put a drop in the bucket that is Oblivion. For time's sake though, I'll only give you essential details. This game is massive, in-depth, fun, and totally worth it's price tag. Go get it. You will love it. It's a must own for any age.

Miscellaneous Information:
Down-loadable content is available and is equally amazing. The game also displays in up to 1080p.

Thank you for your time and I hope this helped!