First off, it's no toy. It's a serious professional tool.
My previous iPad was the third generation (which goes a long way to demonstrating the relatively long life of these things), and I've used it for several projects, both animation and illustration. My main complaints involved inaccuracy with the stylus and the fact the the usable drawing area was a little over a half a normal piece of paper. I've tried about five different styluses (stylii?) and wasn't too enthused about any of them. I even got a glove and cut holes for my fingers so I could rest my hand on the screen and still draw. I also tried using Astropad, which makes your tablet a wifi version of a Cintiq, but was not really enthused about the results. I was determined to get a Cintiq if the iPad Pro, long a beast out of rumor, failed to deliver. The cost is similar, with some benefits and disadvantages to either. I should add, my hands on experience with a Cintiq is very limited, though I've used Wacom tablets for over a decade.
So first, I got my iPad Pro, and I was impressed with it from the start. Even using a simple stylus, the drawing experience was a big improvement. The accuracy was much improved, and of course the extra space is so much easier to work with. It even has very good palm rejection in Procreate, my go-to drawing program. The on-screen keyboard was hit or miss: some programs had the old keyboard, and if I was in landscape mode the keys were too far apart to thumb-type, so I had to set it down. With the new keyboard on other programs, I'm constantly looking to see which one I'm using. Battery life has been great, but it wasn't really a complaint before. And the speed is an enormous improvement, not just in drawing but in simple everyday tasks. Also, Astropad came a lot closer to my earlier dreams of a Cintiq replacement. I realize that for speed and battery life, comparing it to a three year old model is hardly fair. However, even without the accessories, the iPad Pro was a big step up (no pun intended).
Next I got the Pencil. This is the stylus from Apple with pressure sensitivity, designed to work with the iPad Pro (essentially doubling the 'subsystem scans' to ensure low latency). It's a great stylus, very responsive and good 'screen feel'. But unlike most other powered bluetooth styluses out there, it has no function buttons. I think this is a serious oversight, like assuming no one would want a three button mouse because one button is more sleek. Also, the cap covering the charging end has no where to go when you're charging. It feels like it's just sort of hanging around, waiting to get lost under the sofa. And the idea of plugging it into the iPad to charge creates an awkward bundle, and feel fragile enough that I wouldn't do it if I was moving around at all for fear of snapping the plug off in the port of the iPad. It does come with a small female-to-female adapter, so you can charge it from a cord, but again, there's nowhere to store it. There's also no clip or strong magnet or anything to keep the pencil attached to the iPad, and the perfectly smooth and round body can just roll away. For drawing, it is a great stylus, and I really enjoy it, but it seems like a series of weird false steps from a company known for innovation.
Lastly I got the keyboard cover. I was assuming this was going to be the item I used least often (as anything but a cover), but it's been growing on me. I'm just starting to get a hang of the origami folding action so I don't have to figure it out every time I take it out or put it away. With the cover open in 'keyboard position', the iPad feels very stable, and I have been able to type with it in my lap while sitting in a waiting room chair. Not that I recommend that, but it was doable. There is only one angle for the screen, which may be an issue, I don't know. So far it's not been a problem. The typing action on the keyboard is great! I really find myself enjoying using it as much as my laptop keyboard. It also brings keyboard commands to iOS, things like Command-C for copy, or Command-Tab for the application switcher. So far I'm liking the design of the keyboard case much more than the Pencil, which is unexpected.
Closing thoughts: The iPad Pro is not a laptop killer. Many of the applications I use on a daily basis don't have an acceptable analog on iOS. And for long form typing, I'll probably still revert to my laptop or desktop. But darn if it isn't getting close. If you have the money to spare and are thinking of a tablet for any art application, I would seriously recommend it. Even for more prosaic tasks like note taking, data entry, presentation or other highly mobile use-cases, it is worth a look.