Fantastically enormous and so open-ended, you will be in awe...
As all other reviews begin, you start the game in the Dungeon and have an encounter with the emperor, who explains that you have been in his dreams (that's a little creepy). You are are led into a secret passage and on your way to escaping the dungeon, and fullfilling your role in the epic quest. During your escape, through dark caverns and dank sewers, the game runs through some tutorial popups, that help familiarize yourself with the controls. As you make your way through the underground passages, you get a real feel for all the fine details that went into the game. The lighting is amazing (you see sun rays peeking in front holes in the ceiling, and reflects on almost everything), the smoke and mist effects add a foreboding sense to the atmosphere, and the textures are extremely life-like. Amazing look and feel.
On a minor note, regarding the controls ... the tutorial was confusing at times. It never went over how to drop items from your inventory ... it told me I was over encumbered, but not how to un-emcumber myself (I had to go through the manual to find out, and I HATE doing that). Also, the lockpicking wasn't detailed enough. The tumblers wouldn't stick, and I wasn't EVER quick enough (I thought I was doing something wrong, but it was just because my skill was too low). However, these were two minor concerns with the beginning of the game.
After making my way through the introductory/tutorial mission (escaping the dungeon and getting the main quest from the emporeror), I had my first chance of experiencing how really BIG the land is. Over 16 square miles of running (and horse riding), all so you can explore and experience the world of Oblivion. The landscape is lush and amazingly detailed. The grass and trees sway in the wind, and the various floral and fauna scattering the land is diverse and colorful. Ruins, mines, towns and cities are spread all over, so you are constantly stumbling on new places. For the first 3 hours, I was in a state of awe. The beauty was capivating, and the size of the land is almost unbelieveably enormous. Plus, the fact that you can pickup almost anything, and the physics are so dynamic, make this game an amazing achievement.
The combat is pretty good. Unlike morrowind, where you could only attack, and your hits were based strictly on stats, Oblivion got more intense. When you attack, and your sword hits, it causes damage (how much depends on your stats). Also added, is the ability to block. At low levels, you still get some damage when blocking, but it's certainly less. Overall, the new system works well. I also love the fact that if you hit something, it reacts (hit a chain, and it sways ... hit a dead body and it reacts)
As for difficulty - there is a difficulty setting which you can adjust in the options. However, because the game is so open-ended, you could end up stumbling on a cave of really mean monsters ... but, in my opionion, this adds some realism (and causes you to be careful with your encounters).
Visually, magic has taken some great jumps forward. However, on the back-end, it appears to be much the same (but it was good to begin with). Alchemy and Enchanting are similar to Morrowind, but you have to be in the Mage's Guild and attain a certain level to do either.
On a bad note, I have a really good system (not GREAT, but good), and I still have to run the game on lower setting. The game has never crashed on me while playing the game (yet), however, everytime I quit the game the program I get a "this program has quit unexpectedly" error (which doesnt both me at that point, since I'm quitting anyway!).
I'd write more about the game, but it's time I started playing again ... Morrowind was a game a really enjoyed and spend days playing. Oblivion I truly love and will probably cause my girlfriend to break up with me! This game is amazing. I cant say enough good things about it.