ZBC wanted to know if I was enjoying Sculptris, my answer yes but I would enjoy it more if they were actually updating this program, It has a number of glitches and could use some updates and new features.
It is free. I'd say sculptris is more an entry point into sculpting. They give you a lot of the main tools and let you realize the potential in the same way "lite" apps do the same thing. I would go out onto a limb here and say that pixologic has designed a solution to probably every problem youve ever encountered in sculptris, and included it in zbrush.
Its kind of tough to pinpoint a single feature that would add the most to sculptris in my opinion. But if I had to choose I would say either boolean operations which would allow you to knock out shapes using other shapes, or clip and trim curves which allow you to cut out sections of your model by literally slicing them off like a piece of clay.
I feel sculptris was gimped by being bought out by pixiologic. Right now it's a really neat app (with loads of possibility) but not really useful for practical work, at least in my experience.
Well I can't afford ZBrush, so them putting all the fixes Sculptris needs in it doesn't help me.
I use sculptris to hammer out the large basic shapes then move it to blender.