I've watched a bunch of tutorials and reviews etc...here is a good one from 'The Photoshop Guys' (parts 1-4) Articles by | Layers Magazine. They lay out most of the new features and why it's worth upgrading.
Dislikes - the new tabbed layout, that can be turned off though.
Likes - everything else. I've been using it since it came out and love it. The new tools that come with ACR, graduated filter and touch-up brush, are enough to make it worth upgrading.