The transitions to the different keyframes is a bit rough, (Doesn't ease much.) and it might have been better to not return to the default smile until the very end. It's a very 'toothy-/smile-y' mouth, and not that suited to being in a talking cycle-thingie-whatchamacallit. And bouncing to that defauft and back to whatever other keyframe was didn't look that natural or smooth.

The tree in the back gets bumped several times, and while the background stuff is entertaining, having to deal with so much caused the animation quality to suffer. (I have the same problem) And I think I've heard the joke before...