I can't help but notice the edges of his bubble - top left - are very polygonal. Or well defined, whatever you choose to call it. I think they should probably be smoothed off, or something should be done to cover that up.

As for other crits, I've none as it is rather short and hard to really see what will be coming.
But everything seems to be shaping up very nicely, the colours, and style are great and i love his motion so far.
Very mischievous.