It can do pretty much everything
I purchased Zbrush so I can continue 3D work on my own after I graduate college. I won't have access to the student version of Maya anymore but it doesn't matter because I have Zbrush. I can do all of my modeling (hard surface and organic), retopology, texturing, UVs, exporting maps...the list goes on. Zbrush is the future and almost your entire pipeline can be done in this single program with a smooth workflow.