The BDZ piece:
1) I agree with hsn2555 about the glow effect. It's not pixeled. The background gradient is also not pixeled. Having that many colors sort of defeats the purpose of pixel art.
2) It's really big. You could probably cut the resolution in half and get the same level of detail into it, and I think that would be a good idea.
3) The lighting is all over the place. You've got light coming from four or five different directions. Top fo his head is lit and a shadow is directly below him on the ground, so I'm assuming a light directly above him. His face is lit in such a way that makes it look like he's facing a second light source. The fireball itself is a third source, but the hand above the ball indicates that another light is off to that side as well, his other arm has light coming from below him and some of the shadows seem to indicate that there's a light source at some position that's slightly above the point we are viewing this from. So basically, you need to define your forms more. Start with just the flat colors and add one shadow color and get those forms blocked out and solid-looking with only a couple of light sources. The ball could be one. Another one from above somewhere would work.
The ball might be a good way to get some warm / cool lighting in there as well... have the ball throw warm light and the other light source throw something a little cooler at him... Or maybe the opposite of that....
The Sprites:
I'm just gonna crit a couple things on it. It's an improvement over the larger piece. There are still some lighting issues, tho, mostly from the way you animated it. The arm moves forwards and backwards on the running animation, and the shading stays the same the whole time. The legs have the same problem. In one frame the lighting is coming from above, and a few frames later it's coming from below.
The motion is great, tho. The legs especially move very well. Very fluid. The head and arm both feel a bit detached from the body.
Some of the pixels on the top of his head change color on a frame or two of the run cycle.
Overall, tho, if this really is your first pixel stuff, then you did pretty damn well, especially on the sprites. You'll have mad skills in no time if you keep it up
