Finished assassin's creed 2. I hated the first game, but thought there was potential there for something great, and AC2 was a step in that direction. Biggest improvement to me is that they at least removed redundant crap like eavesdropping before getting to your target. Game just had better pacing once you had all your abilities. Which took a while! Some people seemed to really hate the slow start of the game, but I felt it served as a good introduction to the setting and characters. Overall the cutscenes were way shorter compared to AC1's scenes full of ramblings and monologues. Story goes deeper into batshit insane territory with the Subject 16 stuff, but it's not in MGS territory just yet.
I also liked the main villa hub and village. Renovating and upgrading there was useless, but I ended up having a complete art gallery and armory anyway. Just for the heck of it. I see Brotherhood takes this concept and expands it to entire city, which is nice.
One thing that remained unchanged from the first game was the abundant number of viewpoints. I really don't see the point of climbing semi-high towers, when you could just have 4 big cathedrals be the viewpoints for the entire city. There's a total of 73 (!) view points and that's just too much when their only use is to clear up the map.
One thing was actually better in the first game: the road to and actual axing of your targets. In AC1 you could really get some satisfying stealth kills when your planning was good enough, but here getting to targets unnoticed was noticeably easier and didn't feel as satisfying, apart from a few exceptions. They were just easier to reach.
I hear Brotherhood takes the improvements and builds on that, so I definitely want to play it some point. It's good that the team seems to learn from their mistakes bit by bit. Could be that with AC3, they finally really nail the formula.