The swipe area is very small on the vertical axis and there's also some risk of hitting in-app buttons, especially if apps place buttons at the bottom — although I guess this is discouraged. It's especially annoying when using a phone cover. And I like mine - iPhone would be unusable for me without it because it's also much more fragile than all my previous budget Android phones.
Will try getting used to it though.
Re your "It's a mess" comment: I've never had a problem with the android back button, it always did exactly what I expected and it was easy to build an intuition for it.
The context-dependand behavior always seemed very well thought-out to me, because I never ever had to think about it.
> the buggy text selection (editing URLs is a chore, holding the spacebar to move the cursor is broken when you move too far...)
I'm right there with you on these.
> positioning the unreliable sometimes-available back button at the top left has made me drop my phone at least once.
As a person with small hands, I hear you. I miss the days of the original iPhone which was probably >90% usable with a single hand.
Even the discontinued iPhone Mini was too large - which I suspect has been most of the reason of its "failure". Comparing with larger phones, the smaller screen is a downside, and it came without the upside of actually being a single-hand device so it's more or less lose-lose.
Also this has always bothered me before switching whenever I used a friend's iPhone for a moment.
The trouble alread begins when some link in Safari opens a 3rd party app.
Sounds weird, but Apple could really learn a lot about UX from Google regarding this "go back" interaction.
It really was a joy how reliable it works even for inception-level nested app interactions.
On iPhone, half of app switches (at least) require me to swipe up or go to the home screen.
And positioning the unreliable sometimes-available back button at the top left has made me drop my phone at least once.
For all that's to like about iOS, "navigation patterns" are not one of them for me.