1. The Wii is a generation behind in terms of horsepower and so forth, mostly.
You tend to get more content with PS3 and 360 versions of games than with the Wii versions. In fact, in many cases the Wii version is so simplified and stripped down that it's not even really the same game as the PS3 and 360.
So you're kind of getting what you're paying for among the various consoles.