Assassin's Creed 2 has much improved from the first AC. I loved the first game and the second blew me away just like the first. Graphics are top notch, voice overs, terrain, music, ect. all great. If you enjoyed the first you will love the second; if you didn't like the first game... don't get it or write bad reviews about a game that you knew you wouldn't enjoy from the get go.
I wasn't a fan of the first Assassin's Creed. This is almost a different game, it's the same in a lot of ways, but much improved. The ability to use any weapon from any enemy is massively helpful, along with some of the gadgets Leonardo Da'Vinci fabricates for you to mutilate. The free-running control scheme is a bit choppy at times, but the fighting is almost flawless. Everytime you see a new finishing move you will wince at the sheer brutality of it. Lots of trophies to be had, a platinum isn't impossible for those motivated enough.
Overall, just play this game.
Oh the puzzles are wierd and frustrating, but are optional so as not to impede gameplay.
The only reason I gave it a 9 instead of a 10 was because the game screwed me out of a trophy.