Well, ZBrush is great, if you can crack the incredibly obscure UI. Really, its like a tool from a different dimension made for some alien mind to understand. It's clearly NOT suited to be used like I do: open it once every 3 months to work on something I cannot do in simpler tools. By that time I need to relearn even the simplest things, because ZBrush seems to be unable to follow ANY industry standart (they think they can SET them, which given ZBrushs reach among 3D artist, is a fair assumption).
Once you get the hang of it, its extremly powerful though. Worth the 800$ you spend on a license if you ask me...
...Though I have to make a mention of 3D Coat. A tool for less than half of what ZBrush charges you, which is able to do pretty much everything ZBrush does. Its not quite there yet with ZBrush when it comes to sculpting. You can do almost everything, but there ARE some brushes I do miss from ZBrush, especially the more special ones to create realistic Rock surfaces for example. On the other hand, the UI is WAY more intuitive, it supports 3D Mice (which ZBrush still does not after all these years and even Blender supporting them), and you can come back after 3 months without having to relearn everything.
Oh, and 3D Coat definetily blows ZBrush out of the water when it comes to texture painting and retopology...
Before you commit to ZBrush, give 3D Coat a look. you can get a free trial, just as with ZBrush. I ended up getting both, definitely not regretting it, but in the end I use 3D Coat as my go to tool for 3D sculpting, retopo, UV manipulation, and texture painting, whereas I only fire up ZBrush when I reach the limits of what I can do in 3D Coat, just to see if ZBrush gives me the missing options (which it surprisingly does most of the time). But 95% of my time I am satisfied with 3D Coat, and happy that I do NOT need to fire up ZBrush :)