An amazing game beginning to finish. (spoilers included)
Now for a more comprehensive breakdown of the individual elements. Note: although most of my beefs with the game will be irrefutable issues that anybody can agree with, some of it will be subjective as well, so just think what you must of it and make a decision about the game for yourself.
Gameplay
I absolutely loved the gameplay. It keeps and improves upon what I enjoyed in the first game while effectively dealing with areas that weren't so great. Gone are the yelping, helpless women and old men being harassed by soldiers; no longer do you have to do the same kinds of recon missions in order to get access to your target (this made the first game feel repetitive and artificial). Instead, everything seems to make more sense now and flow better; rather than doing the same kinds of observation missions for nine different targets, you do more reasonable tasks, such as clearing away archers or planting soldiers in strategic parts of a city before a mission.
The combat is close to the same, and I wish I could say it's made it harder to defeat a dozen enemies, but I was still able to counterkill and bring down all my opponents. True, not all weapons will counter others easily (believe it or not, it's easier to counter an axe-or-spear wielder with your bare hands than with a sword), but if you know to switch weapons and such, you'll easily be felling enemies as they strike (provided you get the timing down). Still, if you enjoying the gruesome kill animations from AC1, the ones present in AC2 will more than satisfy you.
In addition to all this, there are things to do on the side. You can beat people up, deliver messages, race other freerunners' best times, or assassinate random targets by request from your primary benefactor in the early parts of the game game, Lorenzo de' Medici. There are also "tombs" throughout the different cities dedicated to important assassins throughout history. These provide a fun distraction from the main game, and although they are linear in nature, they are fun to navigate. I had lots of enjoyment trying to find "logical pathways" through the various levels, but in the end, none of them were incredibly hard. Still, the reward for exploring all these catacombs is greater; exploring the Assassin tombs will not only get you lots of money, but acquiring all the seals will give you access to the amazingly effective/badass Master Assassin garb created by Altaïr himself. There is an economic system which allows you to buy cool upgrades, weapons, and change the color of your outfit. If you're smart, money is easy to come by in this game, so you'll have a fun time trying out the various options.
The movement about the environment is everything it was in the first one, and more. There are a few new freerunning moves, but that's not all there is to it. You can perform enhanced air assassinations, you can swim, you can pilot gondolas, and on a specific mission, you can pilot Leonardo's flying machine (which, sadly to say, was rather constrained rather than exhilarating, but I still enjoyed it). There is no longer a vast wilderness that you have to traverse in order to "find" the next city, nor do you have to keep returning to a home-base to get the next mission. Everything's changed.
Now, there are some oddities I've noticed (and these are actually closer to cinematic quirks). For instance, on one mission, you're supposed to shoot a target from afar during a fireworks display because you can't get close to him, but as soon as he's down, it immediately enters the Hall of Memory sequence (where everything is blocked out, isolating Ezio and his target), and it shows Ezio holding the guy just above the ground and talking to him. Then when the sequence ends, Ezio is on the shore again, far off from the boat. How'd THAT happen? Or another time, you're supposed to assassinate two guys in succession, but when I killed each of them many meters apart (one of them had continued running on after I'd killed the first one), the Hall of Memory showed Ezio with both of them laying next to each other on the verge of dying. Magic, I suppose.
There are other things I could mention about the gameplay, but none of it is so major that it detracts from the game, in my opinion. Overall, the game feels great, plays great, and is delivered fantastically. Good job, Ubi.
Visuals
The first game had great graphics, especially considering the scale of the game universe; not only was it massive and detailed, but it wasn't like GTA4 either, where there the game world was huge but had many plain, shiny buildings (as opposed to many detailed buildings with individual handholds and protrusions for climbing; that must have taken lots of extra time and power to implement). It was truly next-gen, the animations were slick, and much of it looked quite beautiful. It wasn't on the level of Gears of War, but I needn't mention that although Gears of War 1 and 2 have some of the best graphics on the 360, they confine the character to narrow pathways and the only interaction with the environment (apart from pulling levers) is ducking behind cover that is conveniently the perfect height to crouch behind.
So, the first game pulled off great graphics for its time. I wish I could glorify the visuals in this game more, but... my praise can only go so far. The game looks good in many instances, the environments look vivid and alive, and the cities look beautiful and convincing, but there are some glaring issues (at least, glaring when my AC-hating brother points every little imperfection out). It's quite acceptable to see visual glitches in gameplay (where anything can happen), but in this game, there is clipping during cutscenes, cheesy animations (such as when the guard kicks Leonardo on the ground), and some elements look just plain fugly (case in point: some of the character's hands). There are other graphical imperfections, but as I try to justify it, the game makes up for it in the detail and scope. I'd like to see Gears of War pull off a game of this scale with the same level of graphics and still maintain 30 frames per second! Yeah, that's what I thought.
Now, the interaction between character models isn't the only thing that bugs me on occasion. There are strange things during gameplay that just look quite amusing. Like when Ezio drops a person's body off a building, it falls down and then kinda "lurches" as it suddenly falls faster, or something. I can't describe it, but that's probably due to bad physics. The ragdoll physics in this game are quite atrocious. I don't know if this is a legitimate complaint or if this is some compromise Ubisoft had to make in order for the rest of the game to run smoothly.
The water is now traversable (yes, Ezio can swim), but it's kinda behind most of our modern-day games in terms of realism. It looks like water with food coloring in it, and it doesn't reflect the environment at all. When Ezio jumps into it, there is a slight splash, but not countless ripples emanating from the point of impact. Gondolas don't split the water as they travel along. And to add to the "food coloring" comment, you can't really see very deep into the water. I may be making an unfair complaint, but I thought I'd mention it anyway.
In other areas, graphics junkies may find themselves "cringing" when they see something that looks like it's from a PS2 game. Like a certain white-haired Assassination Target in Venice who wears a purple robe with "fur" on it. The fur looks like a PS2 texture and his hair clips right into it. I don't want to be too critical, as Ubisoft has done a better job with this game than I ever could, but I'm just telling you what's there.
Anyhow, the graphics look pretty good overall. Ignore everything I said, play the game again for yourself, and appreciate what it does have (which is a lot). I'm not picky with graphics, but that doesn't mean I ignore certain things that are quite blatant (especially my brother points out everything he dislikes).
Sound
I don't have to get into too much detail in this, but I'll write it anyway. The music is beautiful, always fits the mood, the sound effects are convincing, the voice actors clearly know how to dive into their characters, and overall, it's very well-done. However, you may occasionally get irritated by Ezio's constant grunts when he's doing strenuous freerunning, but if it were me in real life, I'd probably do the same.
Story
Since the story is one of the chief elements of the game, I felt I had to talk about it. And let me tell you right away, this game's plot will probably tear down and destroy all previous expectations and theories you had. But that's a good thing. If you played the first game, you will immediately guess that the story will start out somewhat normally and end up with you saying "WTF" to yourself (similar to Knowing, but not ridiculous). And let me tell you, the story is very good; it could rival a good novel. It does a good job incorporating historical elements as well as artistic licensing. I must admit, toward the end I kinda got a weird feeling about it. Kinda like the transition from Pitch Black to The Chronicles of Riddick, where it went from a guy surviving nocturnal alien creatures (somewhat believable) to fighting a demi-god leader of an transcended race, but not nearly as lame. Still, let me tell you, I thought the ending of the first game was weird (I mean come on; a glowing highly-advanced lightbulb projecting a holograph... in the year 1191??), but THIS game tipped the scales. Whether it turns out good or bad remains to be seen.
Some elements are a bit odd, if you ask me; the devs said that part of the plot is Ezio getting revenge on his enemies while watching out for his mother and sister, but in reality, he leaves them at Monteriggioni and isn't required to visit them at all for the rest of the game. Plus, they don't age with him at all (even though the game takes place over 22 years). In fact, no one ages with Ezio, in spite of the fact that Ezio goes from being 17 in the beginning to being 39 in the end. And the "historical characters" mentioned to be in this game don't play such a huge part, save for Leonardo. Caterina Sforza is in this game, but the only interaction between her and Ezio is when he rescues her from a rock out in the water that she mysteriously stranded herself on and she gets him passage to Venice in return. And Machiavelli is hardly in this game at all except at the very end, when he randomly appears and reveals himself to be an Assassin. Strange.
Overall, I love the story. It's complex, deep, satisfying, and surprising. I had plenty of moments of awe when certain pieces of the puzzle clicked together in my brain. In story-driven games, I become almost overly-focused on the story, and this game has certainly satisfied me in that regard.
Overall
The first game was one of my all-time favorite games. I played through it seven times, but that was because I focused on the plot rather than on the repetitive nature of the gameplay. This time, I have the best of both worlds. I probably won't play this game through as many times, and I certainly won't start my second playthrough for a while, since it is so lengthy (and that's what I say after blasting through the game). Great gameplay, great sound, nice visuals (those issues I mentioned don't even matter), and a fantastic storyline definitely seal the deal for me; I can't help but give a favorable final verdict. If any of you were put off by Assassin's Creed, bear in mind that the sequel goes above and beyond it and successfully corrects the issues of its predecessor, so try giving it a twirl sometime soon. Whether you're about gameplay or plot, this game is for you.