I agree - I can see in Bartnell's work some of the same problems I encountered with animation. You don't see those unless you know exactly what to look for. There's the way the girl's wrists move on the nails, more than they should; and he gets by the fact that her hair will swing right through her shoulder by making that head-drop happen very fast so you won't see it. None of us is perfect at this stuff.
All of us went through a learning curve to be able to create anything with the software - maybe me more than most, because I started with Poser 2.0 I think, back in 1996. Here's one of my first creations from 1997:
It just doesn't get any worse than that, but the software was a big part of it. No hair for any of the figures, don't think the eyes would move, and in the version prior to this one, the figures didn't have toes. Poser would choke on a scene with more than a few megs, and it crashed all the time. The figures themselves were rendered nude in Poser and I painted on hair, the shorts the guys are wearing, the cross, those nails, then composited in the hammer and background pic, all in Photoshop. Today, I never do postwork in Photoshop - my pics are all straight Poser renders with no retouching. Your stuff is GREAT in comparison to where I started.
Poser was famous for crashing right up until maybe the 2010 version, which was pretty stable. Even so, it's always a good idea to get in the habit of saving your work frequently! Crashes for me have been pretty rare in the past few years, but you never know. I suspect that DAZ Studio hasn't gone through enough versions yet to be as stable as Poser. I don't use it, so I can't say for sure.