Tl;dr - how much of user frustration comes from user error?
In larger cases (e.g. photo editing, coding) I simply haven’t bothered to learn proper behaviour for using the iPad. Which is a bit silly and entirely on me… the tools exist. But I prefer a desktop for those elements (my MBPro is attached to a dual 32” monitor setup) and every attempt to replace a desktop with an iPad (yeah, I’ve been that silly) has faltered before I got to using Pixelmator et al. With that out of the way…
Although there are not yet many examples on this post, they embody my own frustrations with the iPad as a “workhorse” (makes it extra silly that I sprung for the 1TB M4 11” model but hope dies last…) and those relate specifically to use cases between apps - sharing data, posts, etc. Some of these might be fixed by now! I gave up on that mode of working the iPad… so I guess that’s also on me, kind of.
Attaching the iPad to my Studio Display results in an always on display, even when I put the iPad to sleep. To each their own, but I don’t enjoy having my displays on 24/7… and scaling the iPad to 27” doesn’t result in more real estate, just in a larger version of my iPad screen (or didn’t; although Apple didn’t mention anything at WWDC, iPadOS 18 might resolve some or all of these issues).
As I’ve mentioned elsewhere, Split View and Slide Over (SVSO) are an all-or-nothing package, and I hate Slide Over… but those are ultimately fixed by Stage Manager (SM). Except the loss of screen real estate on an 11” iPad is a bit much for my taste. Now that I’ve typed that, I’ve also turned SM back on and will give it another try. They did change how one engages SVSO in iPadOS 17, so perhaps it won’t frustrate me anymore by engaging SO when I want SV… but I’ll only figure that out if SM frustrates me into turning it off again…