The vocal harmonies in this game has to be one of the BEST features to grace a music game since the development of the genre. A vocal only video game with the harmony system in place would be enough to sell me, but the fact that it's thrown into a full band game, AND it's The Beatles is an absolute killer.
On to the topic, I made this thread to remind everyone who hasn't tried the vocal practice mode to give it a whirl. If you think vocal harmonies are too hard, get a friend who knows the lead and jam out with the guide pitch on to the harmonies. Learn a thing or two about vocal harmonies, and take that stuff into the real game. Nothing more satisfying than getting Double Fabs while jamming out with guitar and bass.
Seriously, get up on it. It's no joke.