Mediocre
I understand it's your second Flash, but I measure everyone by the same yardstick. If we cut you slack, what would be your motivation to imrpove? :)
In any case, this was rather short, with amateur graphics and not much animation, though I will give you credit for lip synching. The ending itself was a bit disappointing, and not because it was an IOU; you need more of a buildup to make the ending funny. As for the bad mic, you might try taking your recording and adjusting it with a sound mixer; ask around to see if there's any useful techniques.
It wasn't horrible, but it left me wanting. Keep trying.