Personally, I don't think it's the best iPad for my usage pattern at all. It's bigger and heavier, meaning more awkward to hold in one hand while lying in bed or on a couch or whatnot (which is the main situation in which I find myself using my iPad), but it doesn't get more battery life or have any new killer features to justify that. If I want a 13" screen and a keyboard I have a MacBook Air, which is a far better productivity/content creation tool than this "Pro" device could ever hope to be, since it runs OS X instead of iOS. In situations where the laptop form factor would be awkward or bulky, I would probably rather have an iPad Air sized device anyway.

I know that a lot of my points echo the misguided things people said about iPads when they first came out ("it's just a bigger iPhone, what's the point?"). The difference, in my mind, is that a 9.7" screen is a sufficient difference from a phone-sized screen (especially back in 2011 when that meant 3.5" and not ~5") that it enables new functionality. I can do things on my iPad that would be extremely unpleasant or downright impossible to do on my phone. I can show multiple people an image or video clip without having to huddle over my corner and squint at a tiny screen. I don't know what I can do with a ~12" screen that I can't do with a 9.7" screen. I don't think that's just lack of experience with the form factor, because the iPad Pro screen size is very close to a laptop screen size and I have plenty of experience choosing between my laptop and tablet. When I opt for the laptop it's because I need a proper OS and/or proper input devices, not because I want a slightly larger display.