It's an expensive hobby, it's not easy, and the results can be disappointing right off the bat, but I think it's a LOT of fun.
A few of the parts I've cast successfully... the guns are pretty decent, and the vests came out very well (minus the one he's wearing, which was a very early cast and done with far less flexible material than the later ones).
This is the closest I came to casting a full Joe; around the time I did this I was dropping out of the hobby for a while.
You can see the myriad tiny air bubbles throughout the plastic; it's not easy to get them out (in no small part because I was using a very fast-setting 2-part polyurethane). The joints, however, are all functional and solid, and the helmet is removable. That's also Rollbar's head Frankesteined onto Gung Ho's neck to fit into the torso correctly. I had successfully cast most of the rest of his lower body and hands, but didn't attach them.
When I stopped, I was working on a progressive mold to make Barrage-style arms -- actually casting parts of the arm directly into others. I had limited success with it.
Hopefully, I'll be getting into injection molding in the next month or so. THAT will be fun... more expensive, but more promising.
