(Commenting only available during the rating period)
I think you focused too much on the mouth here, there's not too much body movement, and their proportions become inconsistent while moving. Try to get the body animated first, then the face, it makes things a lot easier :)
Why is he setting like a frog..?
Description: two kids playing in their neighborhood playground in acting as super heroes
Experience: 2 years
Time taken: 2 weeks