It may be a little late for some of you to read this but Assassin's Creed is astonishing! I still haven't completed it but that's because I'm actually playing the game, not going through the motions just to tell you if the end is any good. I don't read other people's reviews of games and I don't like to give number scores. What I will tell you though is that it is definitely worth the purchase. As long as you know that assassins operate under stealth and aren't warriors, you shouldn't have issue with the game.
The gameplay is incredable. Altair moves with the grace and ediface scaling abilities of Spider-Man. While it is a shame that he is not as quick to dodge as the web-head, he can kill an enemy in one hit, a fair trade. The graphics are appropriate for the Next-Gen experience. The camera is sufficient for the gameplay. The only camera qualm I have is that at some points I can't control the camera for a quick get-away (after the rescue of civilians). Then there is the combat system. The combat itself is fluid and fun. The targeting system on the other hand is a little too fluid. When I want to target the guy in front of me, the thumstick is off by about 2 degrees to lock onto him, I am targeting (not wanting to) another guy and I don't counter the first guy's attack and end up dead.
The story actually keeps you involved, not revealing everything or all that much from the beginning. Because I expect all who read this to play the game I won't say a thing.
The one thing I absolutely love is that even if I'm in the middle of a mission or battle, I can turn my 360 off and run to work or school without fear that I can't get right back to where I was without much issue. The checkpoint saving system is so much easier than a manual save. It may very well be more efficient.
The above teaser line refers to the stealth gameplay of Oblivion, not the game overall (which I am still exploring after almost 2 years).