A portable second display is also a great use for it. I tried to use it for coding, but I really hate the material the smart keyboard's made of (I own the first gen one so this might've changed since then), I just can't type on it because touching it freaks me out. I hate that the chose that material to cover the keys with.
So with coding out of the way, recreational drawing, reading ebooks and watching movies is mostly what I use mine for. Unfortunately that's not anything close to the original promise of its capabilities.
I love it and I use it daily but the problem is when I bought it, I expected to see some support for professional use for it, too. The strength of the Apple ecosystem used to be their app support by external developers --- so, let's say for example, when you bought a Samsung (or even Surface) device with a bunch of new features compared to vanilla Android (or a touch/pen-based Windows), you could be sure that nobody will ever enable you to use those efficiently so they were a waste of time even to consider as a reason to get the device, on the other hand, going with Apple meant the opposite.
Frankly, it doesn't feel exactly true nowadays. Tim Cook's leadership gives me terrible flashbacks to the Microsoft Steve Ballmer-era.
As far as I can see they are meant to compliment not replace. She does the majority of the work in Adobe Draw on the iPad Pro and then sends it to her Adobe Cloud account to finish in Illustrator. Before the iPad Pro she essentially couldn't do digital work. She is a trained fine artist with deep knowledge of oil and lately water painting. Most of her paid originals work was doing murals or selling oil paintings previously. The iPad Pro opened up a whole new market for her.
Imagine a set of tools that rival Illustrator but with an interface that's inspired by Draw.
That would be my dream come true!
I used to have a Surface Pro 2 and ended up selling it because the native version of Photoshop is so unoptimised for a tablet screen that it ended up being even more of a hassle than using a regular computer.
And I love it for doing architecture diagrams and also making changes to building plans for my home renovation. The 11inch model is also a great portable diary/productivity machine. I also have teachers in my family who use it for drawing and projecting mathematical formulas on a screen for their kids which they then email straight after the class.
They are selling well for a reason because people use them for different things.
Doable yes, amazing not really.
I completely disagree about video editing and audio production. Sure it's doable for small family videos, but absolutely not for anything remotely pro.