Ok, so… let me share some first impressions on ZB4.
Polypainting layers is awesome! Really!
This REC button… i dont dig it at all!
53mil polys, in all 40 or so subtools - in ZB3.5 all in high subd.lvl rotate in the viewport just fine > in ZB4, slooooow ?!
Clipping brushes - awesome! … for hard surface stuff ?!
I cut my troll just for the sake of experiment and this is whats happening… 
… this is sooo funny ?!
All that animation stuff… really! Stupid idea imho. Just to make an interesting turntable ? Why ?
Whatever… the Spotlight is awesome! That one was missing! Really nice!
So far so good… I cant manage to make a decent render but i never rendered in ZB so… its normal 
By the way, i am expecting soon the Pixo guys to release R1, R2, R3… 
Whats with the non stop subdividing when working with layers ?