I tried to use my iPad as a complete production center but it’s like using Linux for making music: It works but it’s a pita.
Probably it’s just me but… for deep editing (changing velocity, fine parameter changes etc.) I prefere a pointing device like a mouse or a trackpad.
Another problem is the inter app connectivity itself. You always have to use Audiobus and/or Audioshare or Dropbox to connect apps or share files which is some sort of a workflow killer.
Since there are more and more au apps available it’s getting better. Total recall, easier connection etc.
But lets face it… an iPad (actually) is no computer. It’s an additional piece of gear with a lot of flexibility and… there are really great and affordable apps available. You can use it as a synthesizer, as a drumcomputer, as a mixer, as a midicontroller etc.
But running more than one or two apps simultaneously might get pretty confusing.