A few things I noticed,
1. Ribcage should be a bit more oval.
2. Find some good ribcage refs, you'll notice that the sternum is only about half as long as you've made it.
3. The spine should be an even curve, not suddenly bend where the ribcage ends, you had it more correct in an earlier step.
4. The femurs (upper leg bones) aren't quite right, they actually plug into the pelvis with a protruding "head" on the side (check refs again). They are also a bit too short, relative to the spine.
5. The pelvis is a bit funny looking too, it looks rather flat. It's a complicated shape, so again get some good refs.
6. The inner lower leg bone (tibia) is a tiny bit too thick looking.
7. The upper arm bone (humerus) is a bit too short compared to the lower arm bones (ulna and radius), but the arm itself is about the right size, I think.
8. The skull is a bit too thin in the jaw, the eyes might be a touch too small, and it has tiny cheekbones.
The pose itself is a bit strange and off balance, I'd look up some real breakdancing moves and try to recreate one of them, if you haven't.
Still trying to figure out what the ambigram says, I think I see an A and an N, looks kinda like ALFN, but somehow I doubt that's it.
