Great game!
This was a fantastic game - it was very well done and I really have no complaints at all.
I have a few suggestions to consider for the next version though:
Map the little DJ's arm movements to the x/y of the mouse so that in addition to the tables the character will seem more in time with the music as well. - Would be cool.
A nice little feature might be to cause a 'skip' if you miss a bar - Depending on how you're playing the sound - if you're using script, you could grab the .position and then use that value plus or minus a random bit on a .start combined with a scratch sound to cause this effect. Maybe... I know this could cause problems with the timing (again - depending on how you've set it up) but hey - they're just suggestions right? :)
Consider adding a virtual crowd - complete with cheers for completing a particularly difficult section or boos if you do horribly.