If AC2 is like AC1, I think I'll pass. It was a good game, but let's face it, for all the steps it took in originality it lost a lot of the essential core aspects that make a "AAA" title. AI was weak (I could kill a security guard in a crowd of people and no one would care), Repetitive gameplay (where as in GTA I could run around the city for hours doing random crap, in AC, either the guards kept getting in the way or I just had no incentive to), Graphical glitches/screen tears/pop-ins, short game life (it's about 10-12 hours in single player but with no multiplayer and no reason to replay that is all you get).
Once you get over the next-gen gloss of AC, it's just an above average game.