Ok, so youre a photographer. Lets just put it this way:
You buy yourself two strobes with a bundled transmitter and only one receiver, and neither of the strobes have send a signal to fire the other or even a sync port to split the recieving signal for both flashes. So really, you only get half the result, therefor, not all that professional. Or another example: you buy yourself some lights to shoot at night but they dont have any modelling lights. How do you focus???
The problem with the ipad is that you cant preview a track that about to play or cue it before you fade in on the main crossfader. The hardware isnt there, thus rendering it pretty much completely useless. I've never done it myself nor have I ever seen any DJ blindly fade into an upcoming track without knowing where the track was when faded into it.
Now, since I already pointed out the applications flaws, im expected hell on this comment as well, simple understanding and logic is not evident in some macrumor members, and call my comments 'non-constructive'
Anyway, this type of software is pure gimmick, always has been. The reason you might see some wedding DJs actually use software like this is because they dont really do any kind of actual beatmatching or technical mixing like you'd see from DJs like James Zabiela.....