Joystiq has reported that Famitsu has reviewed Assasin’s Creed, giving it a high 37 out of 40 score! That is one point lower than they gave to Halo 3 and Super Paper Mario.

From Wikipedia:
The environment is completely interactive, from the people to the historically accurate cities. These cities are populated by many people, and the way the player controls Altaïr affects how the bystanders around him react to his presence. For example, when going through a crowd, if the player lightly moves someone out of the way, it will not have a significant effect. However, if the player throws someone to the ground and kills them, the crowd may unite against him and he will then have to find a way out. Similarly, if the player shoves a person aside, they may shove him back. If he climbs walls, civilians will gather around, attracting unwanted attention from guards.