Overall, the new release is fine. The UI enhancements are pretty nice, and the primary functionality enhancement (mix recall) seems to work pretty well, albeit bass ackwards it seems. The transition for me, was relatively seamless, I installed the new version and it worked, no problems whatsoever. The new AD2 adpacks from XLN were probably worth the price of the upgrade, I got all the weird kits and percussion sounds I could find, plus their best snares.
With the exception of Craig's new amps, vocal align, and the new reverb, there has been no content change whatsoever. If you have X3, you can literally install just the program, help files, and new amps and have everything up to date. More of a point release.
I'm sure that there has been significant improvement internally but beyond a few UI tweaks, not much is visible externally. The first time I brought up the PRV, I LOL'd at the clown mode, but once I zoomed to a normal scale, it was pretty much equivalent to what everyone else does. It's ok, get to parity, fix the infrastructure, then innovate, it's all good. I guess we'll get to see the good stuff once the hard work put into this release is no longer the primary task.
No complaints, the upgrade was worth $150 but it isn't a killer app, yet.