What's wrong with it? aside from being a bit to fast
(http://img.photobucket.com/albums/v646/silly_bob/side02.gif)
I think it's the left arm.
Left hand stays out in front of the body the whole time even though the left elbow comes right back. I think the whole arm just needs to come back a bit to bring it in line with what the right arm is doing.
It's both his arms, not just one. I'd also suggest you shade the sections in various greys (nothing too dark), with right arm/leg as shade one (the lightest), head/torso as shade two (slightly darker) and the left arm/leg (furthest away) as shade three (the darkest).
That way you can see them move more fluidly, and it won't be as confusing when they reach key points.
Thanks for the help,. I'll take another stab at it.
Nice one. :) A couple of things that popped into my mind when I looked at it:
1.It's both arms as Rental Shutdown wrote above and I'll add - the legs too. I'll try to explain myself:
When the leg bends in the knee and goes to the left (that is - backwards) at the last moment it straigthens up. To me this looks somehow unnatural. Even a person stands on one place his legs aren't that straigth (except in the army ;D). So try to make a little bend in the knee when the foot goes backwards and than again a bend when it goes forward. One more thing about the legs - I think the left foot (the one that's in the background) overlaps the right one (the one in foreground). Maybe it's just me and my eyes ;D
2.Arms - the right hand (the one in foreground) looks as if the guy wants to box someone in the stomach. The left one on the other side (the one in background) is trying to do some upper-cut hit.
Like the fact that the head is bouncing :)