The movement of the guy was stiff and unnatural, seemingly because you animated just his position and not the movement of his parts. That never works well. People are subject to gravity and almost never make a strong effort to position themselves so perfectly still.
Don't make your lines so think, especially not the short, disconnected ones.
Also, pay attention to color schemes. Every setting should have one even if the scheme changes over time.
Even though I know this is an experimental flash, I still recommend that you have an overall theme because even an experimental flash is a type of story, albeit oftentimes loosely so.
Lastly, the fall of the character at the end was too constant. Objects increase their velocity as they fall and so your animation needs to represent that.