I think it's kinda fun. I'm not a huge Erol Otus fan; it's a strange sort of very simplified and stylized kind of art that actually is easy to mistake for "amateurish" if you don't know what you're looking for; certainly it's a rejection of more realistic or detailed art styles.
However, I think the gallery linked below is kinda fun. It's got a very nostalgic feel to it, and there's technical proficiency there alright; you just have to know what you're looking for to see it in the interplay of light and shadow, and composition.
I've put one of my favorites up as a sample; a black and white pencil (or chalk; the resolution isn't high enough for me to be sure) image of an astronaut on the moon encountering the skeleton of a prior astronaut half buried in the lunar dust. A very intriguing concept, and very well composed.