The missions weren't interesting, the areas were bland and the story was taking too long to get started. However it does pick up eventually and gets much better and incredibly fun. There are about 5 cities in this game, which is slightly more than the first game, and it also made improvements on many aspects from the first game, like the climbing and stealthy combat.
The face-on combat is pretty much the same, except fist fighting has gotten significantly improved. The game is also a lot more diverse. There are a lot of areas to explore, a lot of side quests to do, and even various mini-tasks such as refurbishing one of the cities to the full. One could probably spend many hours playing this game.
So AC2 is better than the first in many areas, including graphics, story line, gameplay and perhaps even the background music too.
But it has some drawbacks however. The controls for example, which were already one of the biggest flaws of the first game, are even harder now. I had to go back to the controls menu to check up on some of them even in late stages of the game. They are hard to memories and they are also very inconvenient, forcing you to hold like 3-4 buttons at the same time just to run after someone, making chase parts of the game rather difficult. I was also not too fond of many of the side quests and such. They were bland and so I ended up mostly just playing the main story.
AC2 is a good game; just a bad port.