I used my new toy quite a bit over the weekend.
I still find it a little expensive compared to a laptop, but you can't argue with some of the apps. So far I've been getting into:
ReBirth - a sort of techno studio reworked from the 90s PC programme. Loved this one in the old days, and its great now with the touch screen
RedBull BPM - great DJ software, very well thought out
Sunrizer - a nice synth. So far not generally impressed with any of the synths I tried, but this is pretty decent. I should give the Korg one a go, but its a bit pricey
Theres others as well obviously, but these are my favourites so far. Not tried any guitar ones so far - waiting for my IO Dock to arrive.