I'm a little tempted, now, by the iPad Pro and the Pencil. It sure would be more comfortable and convenient to retouch photos that way than with a mouse or a trackpad in Photoshop. But I can hardly justify dropping most of a grand just for that, and the other use cases I no longer have - especially with a 13" rMBP in my satchel, there's really not enough point.
That Pencil sure is nice, though.