I made the mistake of upgrading (13 Mini) and it is very clear that the new UI was not tested at all on smaller screens. The rounded buttons take up so much extra margin that actual usable space is greatly diminished.
Same here - on a 12 Mini. My wife and my mother have the same phone, and I have recommended that they hold back on upgrading.
I really hope Apple will address this in a dot-upgrade later this year, but I am afraid that the market share of the 12 and 13 models are too low for them to justify this.
I have the standard iPhone 13 (not mini) and the battery longevity is probably the best of any phone I've ever owned. At over 3.5 years old it still reports 89% battery health and lasts much longer than I need. Previous iPhones I owned were all pretty much on their last legs by that age.
I haven't upgraded it to iOS 26 / Liquid Glass, though, and given what I'm seeing/hearing, I don't plan to.
I just replaced it before the 26 upgrade. It was at 76% by then. With the new battery, I haven’t faced any issues. It lasts a whole day easily, unless I do things like tethering etc.