I really like the addition of subtle resizing effects in the beast's walk animation, and the fact some of the parts' views actually change. In fact, thinking about it, I wonder if it could be done with raster sprites for, say, a DS game?
Cyberdemon is tall and pretty thin and tall. The O is kind of more bulky and those little hands make him even more The O-ish. Also this skirt armor(I really don't remember how it's called) is kind of similar.
The transitions in the perspective of the arms and feet are done especially well. Did you mean to make this loop as jerky as it is? Also, you might opt to adding some body tremor (or fabric tossling) to each step he makes that way the viewers can get a sense of his weight.