Does exactly what all sequels should do: fix the problems of the first and improve on the strengths of the first.
Graphics: The graphics in this game are even better than in the original. The only real flaw is that the cutscenes, surprisingly, don't look as good as the main game. 9/ 10
Sound: The music is very well done, with every track perfectly matching the mood and city you're in. The voice acting is all spectacular and the main character, Ezio, actually has a personality and an authentic Italian accent. This makes Ezio a much more likable character that Altair. 9/10
Story: I really don't know how I feel about the story. It starts out strongly enough, but I found it difficult to keep up with. Aside from certain parts, I almost never knew why I was going after who I was going after. It also falls into the same trap that AC fell into; it gets to be very silly near the end and it leaves more new questiosns than answered ones. I ultimatley stopped caring about the plot, but that doesn't mean it's bad. And, besides, Ezio is so much more likable than Altair. 7/10
Gameplay: If I had to sum up the gameplay in one word, it would be improvment. Everything that was good about the first one was improved and what wasn't good was (mostly) fixed.
The environments are so much less frustrating to traverse, mainly because Ezio can move much faster than Altair while running. (I would also like to say, before I forget, that Ezio does a much better job of concealing his weapons.) There are still some little quirks; Ezio will still (very rarley) jump not in to the bale of hay but to his death. But these are so much less common in the first one, it's almost never a problem.
Your health no longer regenerates in this game. You have to buy medicine from a docotor. Which leads me to the next part: the economy. Early in the game, your uncle Mario shows you the villa he lives in. Below it, the town suffers. So, you can use any extra cash you have to invest in different parts of the town. This makes it so you earn money in the future. And almost everything you buy ups the villa's value. From weapons to armor to paintings, there's no shortage of stuff for you to buy. The opnly problem with this is that later in the game, after you've gotten Altair's armor (more on this shortly), you no longer really need cash to fix your armor. All you truly need it for is to buy more health. Still, it's fun to try to max out the villa's value by buying everything.
One of the biggest addtions to this game is the Assasin's Tombs. There are 6 of them throughout the world and each one earns you a seal that unlocks Altair's armor. Which is pretty cool looking. The only problem I had with it is that you can't dye the armor differnt colors, like you can with everything other armor set.
The tools in this game are... well... awesome. The double hidden blades are easily the coolest new weapons. You can walk up to 2 guards, stab and kill both of them and be on your way without needing to stop. The sword is pretty much the same (although you can use maces as well) and instead of the short sword, you get a knife. There are some satisfyingly brutal finishing moves, especially with the dual hidden blades. (Yes, they are options for combat, and work pretty well.) Other weapons that you don't really need but are awesome just the same is stuff like poison, smoke balls and an awesome hidden pistol. But my favorite thing to do is to climb along the side of a roof, wait for an unsespecting guard to walk near me, climb up, stab him, flip him over the side of the building and be on my way.
There is a new system known as Noteriety. Basically, if you're caught doing bad things ( killing guards, pickpocketting etc), guards become more suspicious of you and after the noteriety meter fills up, will attack you if you linger for too long. And in order to lower the meter, you can tear down Wanted posters, kill a city official or bribe a preacher. While this sounds annoying, it actually works really well. It's much easier to tell when guards will attack you this time around, and the system is just much improved.
Finally, the missions. While you can't choose what you do for investigations, the missions are much, much more varied. They include tailing, sneaking, climbing and scouting. They are much less tedious in this game and are much more fun to play. The actual Assasination missions are much more fun and less repetitive, and are usually more than meets the eye. For example, in easily one of the most fun missions in the game,you have to infiltrate a palace. You can't climb it or enter through the front, so where does that leave you? Well, you can always use Leonardo's flying machine...
Needless to say, the gameplay in AC2 is a huge improvment over the original. 9/10
Final thoughts: If you didn't like the original, this game is still worth playing. Despite the fact that the combat has largley remained unchanged and there is still the occasional movment quirk, this game is a massive overhaul of everything that made the original fun. In fact, it's so improved, it feels more like a standalone game than a seuel.
If you've come this far, thanks for reading.