I dont want to de-rail this thread to death, so im gunna just give my two cents and a link to another thread that'll clear things up for you.
My reasons:
1.) His live sets just include him using his lemur and jumping up and down a lot. Ableton does all the real work for him.
2.) When playing a "live" show (non-festival/rave) he bars anyone else from using ableton as he doesnt want them to out-do him. (
http://forum.ableton.com/viewtopic.php?f=1&t=96339)
3.) He's sort of the new Justice IMO.
I mean yes, he has some pretty nice tracks, and his sets
can be fun (its always a hit or miss with him, you never really know), so as a producer I respect him, but as a DJ he's lost most my respect (for the reasons stated above).
This thread should sum it all up for you:
Okay, Here why I repect Deadmau5