I went from P7 to PP2012 about 3 weeks ago. I did not change operating systems or computers, so this version is the 32 bit one. Without the intermediate step of going to PP2010, it's a bit of a leap, but not so much in terms of how things work or where they are located or organized. The big leap for me was the IDL, GC, and subsurface scattering. I used Bagginsbill's VSS for all my skin shaders and while they work in PP2012, he recommends others. I have experimented now for three weeks to get this down with the results you see here. The leftmost render was in P7, the middle with the scene rendered in PP2012 untouched, and the rightmost with all the tricks turned on. Some postwork on all of them. I'm still not real happy, but the potential for improvement is certainly there. These three have raytracing for the hair turned off. I'll post one other picture that has it turned on below. That feature seems faster now for hair at least.

I would encourage you to go to RUNTIMEDNA and read the forums over there about shaders and such to see how you need to change them. With all these features turned on, expect render times to end up about the same as they were in P7 or become longer. If you don't use all the features, I think there is a noticeable reduction in render time.

I hope this helps.