Its interesting the compare the Wii version of Madden NFL to the XBox version. The Wii version has higher resolution textures and more advanced lighting and shadowing then the XBox version and runs at 60fps (twice the framerate of the XBox version according to reviews I've read).
It will look nice. Hopefully, next year they can ditch the current-gen engine and make one exclusive to the Wii to maximize the graphics. Of course, I won''t go as far as saying it will achieve Xbox360 levels.