Borrows too much from Crackdown but still entertains
Story:
Certainly, story wise, not all is how it would seem, even if you've seen all the trailers for the game. The game's major plot twist occurs within the first 5 minutes and after that the plot gradually gets more and more convoluted. It does hold your interest throughout the game but once you're finished you'll probably be saying "what the hell was the point of all that?" Basically, the story just feels like a cheap gimmick to make you pay for the inevitable sequels.
Graphics:
As a technical showcase the game is quite incredible. Considering the size of the environments, the textures are phenomenal. This is combined with an awe-inspiring level of draw-distance to really create a sense of the size of the cities. At street level the sheer number of NPCs makes you feel like you really are in a living breathing environment. On the other hand, apart from the character you control, the character models are very poor, even for some of the more important characters which you often see close-up in cut-scenes. This isn't a huge problem, but it does standout in an otherwise incredibly realistic looking game.
Sound design:
In terms of sound AC is incredibly complex. This needs to be the case in order to properly create a sense that the cities are alive and its been executed well. Push a guard off a rooftop and you'll hear the pedestrians below screaming. Walk through the streets and you'll hear NPC's talking to each other in the crowds.
Gameplay:
Assassin's Creed basically plays like "Crackdown" for the medieval times.
Platforming requires almost no input at all from the player. Hold A and Up on the analogue stick and your character will scale pretty much anything on his own. It does look visually beautiful thanks to the superb animations but the satisfaction is lost by your own lack of involvement. Comparing it to Crackdown, a similar open-world game, its just not as entertaining in this area.
The basic mission layout in AC provides you with 9 bosses to take down with you free to choose how you locate and defeat them. This is exactly the same as the core missions in Crackdown. Some will say that in AC you have the choice to carry-out these missions in your own way, more like a Hitman game, but you can do the same thing in Crackdown.
On the other hand, the side missions in AC are very unique; involving aiding citizens of the cities and gathering intel on your targets by eavesdropping or pickpocketing NPCs, or sometimes just beating information from them. These missions also suffer though, in that they are extremely repetitive. There are very many of them in each city but most of them ask you to the same thing over and over. Its incredibly unimaginative.
Finally, the game also owes the notion of "collecting flags" to Crackdown. In Crackdown you collect "orbs" which are hidden throughout the city, primarily on rooftops, and these allow you to upgrade your character. The only difference with the flags in AC is that they don't contribute to your character's skills and abilities.
Of course AC has plenty of unique and interesting things going for it as well. The combat is very visceral and satisfying. Its all about timing your blows with the sword to break enemies defences and then striking when the time is right. The finishing moves are brutal and really give reward for your efforts. The mechanics of moving through crowds by gently pushing aside pedestrians are a brilliant idea and really add to the sense of a realistic city. Also, despite the lack of control in platforming, you can't deny that running accross rooftops to escape "Parkour" style is fantastic to look at.
Overall:
Assassin's Creed is a game which owes a huge amount to others that came before it in the open-world genre. Much of it is borrowed from other titles and simply re-applied to the new context of the medieval setting.
On the other hand, even though anyone who has played Crackdown will spot the lack of originality, Assassin's Creed is still a fun game to play and, if you take into account all the side-missions, its one of the longer games released recently. And of course it looks pretty stunning as well.