Need to work on sounds, but animation is nice
The animation and drawing style was rough, but quite well done despite that. It was nice and consistent, and there were no obviously lazy drawings that I could see, while some parts had some nice shadows and good shading.
It was paced pretty well, and as such was entertaining. Had it been slower it would have gotten boring fast, but the rapid fire style of it worked well.
As you say yourself, sound effects were poor throughout. This could have been masked, however, had you used some appropriate music to play over the top. There are plenty of excellent examples right here on Newgrounds in the audio portal if you ever need music for an animation, and it makes an enormous difference.
It would have been nice to have some voice acting rather than speech bubbles, especially as the speech bubble pacing was a touch fast, making reading them all a bit more challenging than it should have been- doable, but a rush.
Otherwise it is a case of refinement rather than all out change- it is always impossible to get better at drawing and animating, so long as the basics are there.
A good effort though, worthy of a pass and a semi-decent score.