I'm not an expert either, but I think he looks maybe a little too clip-arty. I think you could fit a bit more personality/charm/distinct qualities into him, maybe by making him look a little worried or giving him a more distinct posture.
Other than that, I really like your basic concept. He's just a little too garden-variety, is all.
I appreciate the feedback, but I really don't know what I would do do spice him up, or even why I would do it. I decided to go low res for a couple reasons:
The first is simplicity. Not only is it easier on me as the game artist, bit it fits in with the character himself. He's just a scientist. He wears a lab coat and khakis. The main focus of the game is going to be the gameplay, so story is secondary. This leads into reason two: he's not a character-driven character, so to speak. His sole purpose is to interact with the game environment, so he doesn't really need to emote or express himself or even stand out in any way. If it were a mascot-driven game then more emphasis would be given to making the character emotive (as in my Squarebear design).
Even so I did try tinkering around with more detail when I was designing him, like a nose, mouth and pocket protector, but it just doesn't look right without bumping the number of colors in the palette way up, which I want to avoid. In fact, in the latest incarnation I've reduced the number of colors even more by taking out the darkest pants color and the shading on the shirt. The point is to make him look as old-school as possible while still looking smooth in the animation.
Speaking of which I did take vinny's suggestion and added a fourth frame to the running animation, and it does look smoother. I'll probably add even more by the time the game is done. I also changed up his jumping frames so he doesn't look so much like a candy-ass leaping around in a field of daisies.
Anyway, I haven't worked on it in about a week. I'm starting to slack again. I got caught up making background and platform tiles when I should really just be finishing up the engine, and switching gears like that interrupted my workflow so it's harder to get back into it. It's a bad habit I need to break.