I'm considering buying Rock Band The Beatles for my only gaming console, the Nintendo Wii, but I was wondering if there are any big differences between the version on Wii and the version on Playstation 3?
AFAIK, there is no difference between PS3 and Wii version.
The only difference I know for this game:
The Xbox 360 version of "Rock Band: The Beatles" has an exclusive song (All you need is love) which the PS3 and Wii don't have; but the song is available for download on the Wii and PS3.
The only real difference is the graphics and maybe sound quality of the game. More so the graphics though but, not enough for it to bother me honestly.
The only difference is with DLC. If you wish to download the remainder of Rubber Soul, Sgt Pepper or Abbey Road, you must pay for the tracks individually on the Wii rather than a group bundle.