OH MY GOD! Just finished it. What an experience!!! Can't wait for the next in the series!
So you start with a memory that begins the story of Desmond's ancestor-Altair(You). You get out of the animus at some intervals to discuss the memories with the doc and to do a little bit of present day investigation too. The story turns from interesting to absolutely amazing in the end, and therefore im not going to reveal it to you.
In the game you get to travel to cities like Jerusalem, Damascus, Acre, Arsuf and Mysaf through the kingdom on horseback or directly.
The graphics are amazing and the shadows and the textures are greatly detailed, and if you have a high end pc, you'll get an amazing experience.
There are a lot of beautiful scenes that will force you to keep taking screen shots.
The NPCs are very realistic, reacting to every move you make, like commenting on you when you start climbing buildings in front of them or jump from one.
If on a run from the guards for some reason, once you break their line of sight, you can blend in with the environment in pretty cool ways like sitting on a bench, blending with some scholars or hiding in a haystack or a rooftop garden.
The climbing and jumping part of the game is probably what made it so famous and waited for, and it feels great. You just keep a few buttons pressed and the work will be done automatically, but you will still feel as if you are doing some great work. It all is seamless and very realistic.
The city feels very alive, with the sounds of children crying, dogs barking etc. to be heard in some places, plus a huge amount of crowd moving about the city makes it even more so.
The combat part is never very difficult, but it would be an understatement to say that it is just great. You can inflict a number of different blows to your enemies like grabbing, parrying, counter attacking and the like. There may be around 20 people on the screen but you'll be able to kill them all slowly.
Assassination, as required, is one of the best parts of the game, with the hidden blade having its own coolness. You can stealth assassinate in a number of ways too, jumping on with the hidden blade, normal blade assassination, throwing knives (one shot kill, ranged) etc.
Near the end of the game and the final assassination, the similarity of the game is blown away as the plot suddenly twists leaving you dazed. The story, people and environment change so rapidly that completing the game becomes way more than worth it. It is so much fun in the end of the game, that however much you enjoyed the rest of the game, you'll enjoy the last part TEN times more. Friends and enemies all get mixed up to form one smashing climax.
You get out of the animus feeling all strange and VERY entertained, only to know that there is a lot going on in the present day as well. The only thing you will think except what you just saw and did will be - "When is the next game going to come out?"