I feel pretty much the exact same way you do about The Beatles (love a handful of songs, the rest strike me as painfully average/uninteresting). I'm still very tempted to buy this game though, if only to check out the dreamscapes/art design. Plus, the harmonies would be fun.
BUT I say give it a rent or find a friend with it and then see. If you can't replay songs a lot and still have fun with them, you'll probably tire of the 45 song setlist pretty quick.