Hi siquator! Welcome to Newgrounds. Newgrounds is a great website, and I wish you the best of luck in the future. Anyway, let me try to give some on ow to improve:
First of all, I understand that this is a test, and is probably one of your first animations, and if so, it is a very good start. But, the tweens could have been faster (like when he hits the wall) it would have been better if you added some recoil to the hit, and maybe a motion blur just before he hits the wall. And, the drawing could have used improvement, and the line work could have as well. If you don't already, I recommend getting a tablet. I used a bamboo fun for 4 years, and it was so much better than a mouse, 1 week ago I saved up enough money to get a 12 inch cintiq. Any tablet is better than nothing. I think that if you stick at this, you could be great! But the newgrounds reviews will seem quite harsh, so if you get criticism, don't worry, it'll just drive you to improve even further! Good luck!
Bryn