I've just finished Assassin's Creed 2, and here is my review/impressions(PS3)

Graphics 9/10
they were really good, but there were some minor shading glitches, and once camera passed through wall. Cities are really lively and well built.
Animation 9/10
Great overall, but from time to time it was a bit awkward, blade going next to head, without hitting anything and someone dies etc.
Gameplay 9,5/10
Great improvement compared to the first one, Assassination required a bit of stealth, not so many repetitive missions. Twin blades are awesome. but fights are too easy - just counter every hit, and against pole-arms use fists to disarm.
Plot 7/10
Plot was really good through the most of the game, but the ending just wasted a great potential for mysterious story, story that required player to think, for something not so much cliche... to think that the game's plot was fucked up by one short sequence..
Music 10/10
It was just awesome for this game - it always seemed right.
Overall 8/10

Pros:
- Music
- Great improvement in gameplay compared to 1st one.
- Twin Blades
- Interesting characters.
- The Truth sequences are totally awesome. period.
Cons:
- Ending!
- Minor glitches with animation
- being forced to collect codex pages.
- did i mention the fucked up ending?