A great storyline and open world is what makes Assassin's Creed 2 a sequel worth playing through.
Starting from where the first one left off, you take control of Desmond in modern time and escape to a place where you enter the Animus 2.0. Most of the game then takes place from there when you're in control of Ezio Auditore da Firenze, but we'll just call him Ezio. Ezio is one of Desmond's descendants, and basically the whole game is a simulation of Ezio's life Desmond has to go through to gain his abilities and whatnot.
The setting takes place in 15th century Italy, and at first you don't have access to very many areas, despite this being an open world action game. However as the game progresses more areas (including entire cities) are unlocked and can be traveled to at anytime so long as you aren't in the middle of a mission. My first impression was that there wasn't a whole lot of "action", but that of course changes later on in the game. Basically your only enemies are guards which are scattered throughout the cities, even on the rooftops. If you cause any sort of trouble, they will be after you. And like Grand Theft Auto you typically have to run away to get them off your back. You can also just kill all of the ones that are near you... if you can handle it. Overall it's a very annoying process getting into trouble with them. And at times you are better off just letting them kill you rather than fleeing halfway across the city or attempting to kill them all. There really isn't any punishment for dying. The game saves often, and during missions there are plenty of checkpoints. This is a life saver as the gameplay can get quite dull or just plain annoying.
However Assassin's Creed 2 is by no means a bad game. The gameplay just lacks some (for lack of a better term) "fun". The combat is more interesting to watch then actually engage in. It's pretty much L1 to lock onto an enemy, then square to attack. There's also R1 to block, and a few manuevers like dodging and even disarming. But otherwise it's really simple. Unlike the overall gameplay, the story and open world are very much intriging. The environments do look good, and the story was good enough to follow even after not playing the first game. It's just the gameplay that's somewhat disappointing, all though there are some fantastic over-the-top moments. The control scheme was just okay, climbing buildings wasn't as smooth as it could of been, and some of the platforming elements were even kind of annoying, but it could have also been much worse.
On a more positive side Assassin's Creed 2 is full of unique characters, some of which are actually non-fictional. The game is full of historical information to those that are interested in that sort of thing. It was a quite lengthy game, with just the main storyline taking over 12 hours to complete. And just like most other open world action games there are plenty of side quest and plenty of stuff to collect. Those looking just to complete the game will get about 10-15 hours out of this game. Those looking to get all trophies will get at least 20 hours. And those who want to get every single thing out of this game will likely get over 30 hours of game time. The ending opens up the story for yet another sequel, which is a great thing because the story really picks up even more there towards the end.
Summary
Graphics- 9/10
Gameplay- 7.5/10
Controls- 7.5/10
Story: 9.2/10
Sound: 8.5/10
Overall: 8.2/10