[youtube=http://www.youtube.com/watch?v=PuQl8T6ZHmE] Are there other djay apps on the iPad? Sure. But, I've used this one on the Mac and it is easily one of the best.
Most importantly, to me:
Seamless AirPlay integration (wirelessly transmit your mix to AppleTV or AirPort Express station)
So...imagine this. The djay can be walking around the house, mixing the music, in realtime, sent straight to the house system wirelessly through AirPlay.
Seems pretty darn cool.
Welp, there goes $19.99 of the coming iTunes gift card money ;-)
-B