I’ve been using iOS 13 on an iPad for the last week and it works awesome. I especially like the iPhone-size keyboard that you can type on with one hand.
In general, there’s something I like about Slide Over and the Split View approach — its task-orientedness. Especially with Slide Over, you have a main thing you’re working on and some assisting applications on the side. It’s modeled after your focus. Freeform windows invite more distraction. However, like with any opinionated workflow, with Split View and Slide Over there will be friction in some cases, which wouldn’t be there if user would have a bit more control.
Using a touch screen gives me a lot of wrist pain even after 20 minutes of work. Not great for ergonomics.