A friend of mine is fond of it for doing illustrations of scenes from his tabletop RPG sessions. I asked him about it at one point.
The program is free, but there's basically no way to make the actual models yourself - you have to buy each little one, whether by itself or as part of a package deal. They're individually cheap, but he seems to spend a fair bit on it in the aggregate. DAZ studio just scales, places, morphs, etc. the bought models.
The models are extremely high-poly. Like, thousands. They're not intended for animation, even - maybe rendered animation, but not realtime animations, ever.
The rights to use them in anything are extremely questionable, if not outright forbidden.
Basically - don't bother. It's the wrong tool.