It's pretty darn good.
I don't care about the dimensions of the saiyan and all that other stuff.. You're the artist, you can decide how the shit looks and doesn't look. :)
Anyways, it looks pretty good.. The only thing is that it looks a little stale, it's hard to explain but it seems like with him getting cut in half, it feels like there should be a bit more movement on his part..
Another thing is that the hands are a bit too small, at least from what I can see.. I mean unless the arms/bodies are so much more massive than normal (which would make sense, for dbz) that the hands are normal sized and their bodies are just way beefed up.
Regardless, the coloring and anatomy (other than that minor detail) are pretty solid. Great work. :)