I finished this game the other night. It was a good rental, but I'm glad I didn't buy it. The acrobatic gameplay mechanic and the graphics definately felt AAA, and the plot was very cool, like something out of a high-concept sci-fi novel. But the actual game structure felt really lame. You were literally doing the exact same mission 8 times in a row, and when you were finally done, the game was over. It was like playing the demo for a game 8 times in a row. Once you finished the first mission, you'd already seen everything the game has to offer, and after that, wether or not you have fun depends entirely on how long you can repeat that mission before you get bored. And the ending-- or lack thereof-- was crap.
Hopefully this game gets a very well done sequel. But if Assassin's Creed 2 is nothing but more of the same-- which would be VERY redundant given the nature of the first game-- I would be very, very dissapointed.