What is the thing which makes Assassin's Creed a special game?

I went to gamespot.com and I saw Assassin's Creed ( score: 9.0 ), but I don't know why it's so special because I didn't experience it before.
so please for the people who play this game....tell me why is it a good game and why the score of this game is better the Devil may cry's score? ???THANK YOU! :)

Even I think at times that the score is too much overhyped but the sneaky pinches are really awesome in the game as well the hiding tactics other than that its pretty much similar to Prince Of Persia.