I'm quite impressed with what Sculptris already has going for it. Though I have to say more than a little put off by the Quirky navigation. Maybe think about more conventional option, giving the user the option to use Standard or More familiar controls. Brushes feel real nice but once again the Quirky hotkeys give me a headache when it comes to using things fluidly. I reach for Smooth (Shift) and I Dig a hole? that kind of thing.
Also I find that I cannot come out of Symmetry just crashes every time. Still its fun to play at the moment.