Well, the $300 version is for non-commercial use. Otherwise it was something like $700 - there's a few more bells and whistles (able to use more layers, etc.), but basically the same thing.

Yeah, REALLY simple interface and use. Mac users are pissed, though - it's Windows only - was developed by Weta as an in-house modelling tool during midway through LOTR: II to replace ZBrush, and they use all Window and Linux systems, so no Mac version coming.