looks interesting, I like the eyeless look makes them more monstrous and alien.
some crits I don't think the head transitions too well as is, I'd go for more of a bridged gap between the cranium and shoulders, and I know they are really WIPy but hope you are going to do a more organic bent arm/fore leg.
quick dirty edit to illustrate my suggestions:

might be interesting to play with the tail shape size. also maybe even putting a alpha plane with spikes along his spine or just on his tail would look effective oh what they hey hey I'll do an edit:

also if you were to do eyes a suggestion, and if you wanted to keep going with the alpha planes you could do teeth too. (ignore the flow of the wireframes, doubt they match your polys just doodled to illustrate)
anyway keep going it looks interesting
