If you have very large Runtimes (mine are around 20gig~40gig each) P7 crashes when allowed to "build library" - tech support says they are working on that, work around is to navigate folder by folder, one at a time and if it asks to rebuilt then click Cancel (save often!)

alpha channels are lost when rendering over image or shaders - tech support is working on that, there are a couple workarounds until thats fixed.

It renders faster on simple scenes, freezes on larger scenes (mine was about 80meg, nothing fancy). It won't give any reasons or errors, just stop. - the reply I got from tech support is "we are currently working on several issues with the rendering engine"
(example: Haunted Mansion back wall with books, 1 nekid V4, hair, several other book props, three lights, resolution settings dropped to nearly null = P7 freezes 1/3 way after about 4 hrs; P6 completes entire render at full resolution in under 4 hours, plus three other animal characters had been added once success was achived - - - all this data and more has been submitted to tech support once verified)

Other then that I stopped using P7 as I don't do single character portraits often (which P7 seems to do well) and the work arounds for Alpha channels was a pain, the navigating libraries one level at a time was annoying to say the least and the consistant interface lags was all enough for me to return to P6 until P7SR1 is released.
Aside from that, the new lights looked nice but I never made it to some of the other stuff (spent too many weeks trying to accomplish just two rather simple composited scenes that P6 was able to complete in under a week)