See Todd Kopriva's blog for an extensive list of "what's new and changed". Here are just a few points:
- a trimmed, lithe user interface; less waste, more customization including customizable buttons
- OpenCL support (one some systems) for GPU acceleration
- expanded multi-camera editing
- native support for new formats (such as ARRI Alexa)
- basic color grading built-in; integration with SpeedGrade
- improved dynamic-linking
- full-screen playback on primary monitor - yay!
- uninterrupted playback (while you fiddle with timeline, settings, etc.) - yay!
- new way for hardware manufacturers (AJA, Blackmagic Design, Matrox, etc.) to write drivers and interface with Premiere Pro; drivers for popular hardware are supposed to be ready by NAB (April 15)
There will be more; stay tuned.