A brilliant game.
You control Altair. Altair and everything around him has breath taking visual design to it. The game is set between three major cities in the Holy Land: Jerusalem, Damascus, and Acre. Most of the buildings have fairly unique architecture to them, the characters have very good facial and body design, and there are brilliant shadow effects. There is no texture popping, little clipping, almost no frame rate issues, and Altair has nearly perfect animation. If I was to complain about something, it would be the color palate, as it is fairly gray. The gray isn't the doom and gloom type of grey, such as in Fallout 3 and Gears of War, it is a more bright and uniformed grey. There is some color, such as on your character and some NPC clothes, on banners and flags that are plastered around the cities, and a bit of vegetation, but I feel the designers could have been a little bit more liberal with the colourful visuals.
The sound is equally as excellent. The music is designed by acclaimed video game composer, Jesper Kyd (Hitman series, Splinter Cell: Chaos Theory). Instead of the music being epic and over the top, it is fairly under toned most of the time, which is necessary, given the stealth aspect of the game. In fact, most of the sounds of the game are quite subtle. You will hear birds chirping in the distance, and hear mundane conversations between two people among the thousands jabbering in the city streets. It's a fairly nice touch, and adds a lot of detail, without going too far. The voice acting holds up pretty well. Sometimes, a few people of the support cast over act a tad, and Altair himself doesn't seem to emote that much, but it's decent overall.
The story is quite unique. The story actually takes place in the future, with a bartender by the name of Desmond, who is presumably kidnapped by scientists, for the sole reason that his ancestor is a person that these scientists want to know about. This ancestor is Altair, an elite assassin from the 12th century. Desmond is placed in a contraption that connects his memories with the "genetic" memory of Altair. If that sounds weird, that's only because it is. The captivating part of the story is Altair and his connection with his organization, The Creed, and also the questionable targets he is ordered to assassinate. It brings up some pretty neat themes, such as sacrilege, blind devotion, and the repercussions of pride. These themes may not sound very original, but the ways they are blended together and executed make it very immersive.
A big part of the gameplay is platforming, which it does very well at. This is mostly credited to the wonderful controls. Simply holding down a trigger will have Altair run and pressing A while holding the trigger will have him sprint. While holding these two buttons, Altair will jump on his own whenever he comes to an edge and also climb a wall when he is near one. This makes moving around rooftops very easy, and due to the immaculate animation, it also looks very cool. Exploring the map will require you to scale large building, such as towers or church rooftops, survey the area, and then jump one hundred feet down with a rather hilarious "leap of faith" mechanic.
However, this game suffers from what I like to call "Spiderman 2 syndrome", and what that entails, is that the game gives you a free roaming ability to jump around on rooftops, but not many things very engaging beyond that. In order to continue with the story, you will need to do some fairly repetitive side missions, such as pick pocketing, interrogation missions, and eaves dropping. These may seem diverse at first, but they all follow through the same motion of "find a dude" and either follow him, beat him up, or silently kill him. There isn't too much variety between these side missions. They wear thin after a while, and begin to feel like a chore.
You can also save some of the locals being harassed the town guard, which brings us to the combat aspect of the game. The combat is solid, but nothing special. It takes on a fairly slow-paced hack-n-slash formula. It is incredibly simple. To the games credit, it does have a plethora of unlockable moves, but they are not at all necessary. I completed pretty much every combat scenario using only the attack, and counterattack moves. The combat is also very easy, and the way the game forces you into the stealth aspect, is by sending an obscene amount of enemies after you. This method doesn't really make the combat more difficult, just more tedious.
The good thing is, you don't have to engage in combat very often. This is a stealth game, and stealth games usually don't excel in combat, because it's something you typically want to avoid. Altair has a little trick up his sleeve (literally) to take oblivious guards down with one quick jab to the neck with his dagger. This is quite rewarding in assassination missions. Slaying a target with your hidden blade is probably the most rewarding thing in this game.
Overall, this game is nothing short of greatness. It is deep, epic, and immersive; yet at the same time it is quiet and subtle. Despite a few hiccups in the gameplay, it is defiantly a game you will not forget.