If you don’t like iTunes 12, it’s possible to revert back to iTunes 11. Chris Breen explains how over at Macworld.
Personally, I don’t recommend this except to those people who are well-seasoned working with their Macs and messing around with things that aren’t designed to be messed with. It’s a complex process, and things can go wrong. Also, it’s very possible that iTunes 11 won’t work with Yosemite after a future upgrade – or won’t work with iOS devices – so I think it’s best to just stick with iTunes 12. Or not upgrade to Yosemite…