An incredible game with some wasted potential. Deserves nothing less than 8.5, in my opinion.
Gameplay 10/10
A perfect 10. Simply because everything matches up perfectly. Altair can interact with pretty much everything in his environment and that is something rarely accomplished successfully. Climbing on buildings was very well designed so that Altair can grab on to anything he can find, although it did seem a little surreal at times. Like falling from really high and surviving because the DNA synchronization bar is high or being able to climb really high structures with ridiculously few points to grab onto. This makes the game rather silly. I don't think Ubisoft's intention was to make it realistic, because if they did then this is a major fail, but still I felt that I should point it out at least.
Story 8/10
It was pretty decent. While at first sight it may just seem pretty dum because, let's face it, throughout the entire game you just go to cities kill some bigshot, go back to Al Mualim, then go kill again over and over again. No, it is really more complex than that. The interesting thing is that you get to follow 2 storylines at the same time. Altair's and Desmond's. You follow Altair on his quest to defeat certain men that are a threat to your Creed's cause, and then there's Desmond, some random bartender who happens to have vital information stored in his head, that's useful for one of the largest companies worldwide, who has been taken hostage and is looking for answers.
So why am I giving this an 8 even though I just described a very interesting story? Well, it's only because of BOTH characters' stories' endings. I mean on both cases: wtf? Especially Desmond's. I'm not going to mention anything more for fear of spoilers. But man, they better explain this stuff on AC2, but from what I've seen they don't, so that's just one huge plot hole, which really bugs me!
Soundtrack 8/10
Yet another 8. Why? First of all, some of the tracks were rather unoriginal and I felt like I had heard the exact same thing before. In fact a lot of the tracks remind me of Jak II: Renegade. This by no means makes them bad, just not unheard of. Second of all, they didn't use what they had well enough. For a pretty big part of the game there was no music playing at all, and that might not bother too many people, but it certainly bothers me. The timings also aren't very good. I think a great example of that is the first time visiting Jerusalem. There is some great music playing in the background but you reach the city gates too soon and it stops after that to play either something that's not as good, or just play NOTHING. That's just a waste of potential, if you ask me.
Let me mention a few things that really bug me:
First of all: Have you noticed that in most cities somewhere there are people shouting something about King Richard or Salahadin to the crowds? Sometimes they are interrogation targets, and the rest are kinda just there. Why are they annoying? Because I can still hear them from what feels like miles away! And they are even more annoying because there is nothing playing in the background to cover their damn voices! That is so frustrating! This made me SOOO angry during my first playthough! And the game was pretty strict about not harming innocents so that's why I didn't touch them in my first playthrough. Fortunately on my 2nd go, I realised that simply punching them will make them shut up, so that was a relief. But they are still annoying if I happen to be scaling a view point and suddenly I hear some dude ranting on about King Richard or God or whatever.
Second: The targeting system was a little lousy. This is just speaking for the PC version since I haven't played the others and don't know how the controls work there.
Executing battle related commands other than simply attacking requires a lock-on to the target. That can be done either manually or by attacking a target (you'll still have to aim your sword swing to hit the target otherwise it still won't lock-on). However if the enemy attacks you that won't happen. This isn't something major, but still allowed my enemies to get some free hits on me.
However here's something that deprives me of an otherwise very useful function. The game gives you the ability to grab and throw your opponents to the ground. While they are on the ground, you can use your hidden blade and quickly finish them off. Cool right? Not always. When fighting against one enemy you can easily throw him and kill him. However when fighting against multiple enemies this can't be done easily, if at all. Because of the targeting system. After you throw someone you aren't locked on anymore and the lock on immediatly focuses on someone that is still standing. There is almost no way to focus yourself on the one that's on the ground. And that's really bad.
The Bottom Line: Assasin's Creed is definitely a game worth checking out, just take heed of the few points I raised above.