I bought Astropad tonight in anticipation of iPad Pro (it's $19.99 right now, down from $39.99). Tested it wireless and wired with my 64gb iPad Air. Pretty impressed, but I was just doodling in Photoshop CS6 to familiarize with how it works. I haven't tried to pair my Wacom Intros Creative Stylus (original) or Pencil (by Paper53) yet.
For doodling/sketching, painting, I'm thinking it'll be really nice with iPad Pro. And when I'm not around my MBPr, I can use Procreate. 🙂