Reminds me of Plankton. Really good run cycle.

Thank you for the comments! I'll try to work on arm motions.

Haha, I thought I'd forgotten about commander keen, but apparently not :)

I also agree with Hapiel's cc. You could lower the elbows a bit, maybe swing his arms a little more forward. 

He is an alien though, so maybe that's the way they run on their home planet!

I love the motion in this one! Nice sense of weight and character too!

It's fun! =D

Sweet! The bounce thingy on the head is really cool!

Since you asked for cc, but this really is a nitpick:
I think the elbow reaches too high. For a floppy arms effect I'd play more with the lower arm and less with the upper arm, or the upper arm should 'whip' the lower arm in motion. Or if no floppy effect was intended, it is simply extremely high and long in one of the frames.

The big smile, color, eye and bouncy antenna makes me think of the commander keen aliens ;)

really cool run cycle. i can't belive this is the first time.

Oooh yeah, I see it, thanks!

Really fantastic. The only criticism I can come up with is that nearest arm is bent a bit weird in the frame where it is fully extended out the back.

Terrific first time run cycle. Many take a long time to achieve this level of quality.

This is SO SMOOTH! Can you take a look at mine and tell me what I'm doing wrong?