that was the last android phone I owned.
The differences between feature sets on different generations is less and less it seems though. If I recall correctly, the differences between the iPhone 3G and iPhone 4 was bigger than for instance iPhone 6 and iPhone 7. If I weren't such a sucker for new and shiny things, I'd probably buy an iPhone SE today.
Killing 32b-only-applications i do not like :/
As for speedup/memory gain, merely launching a 32-bit app will cause the OS to get a bit slower / use more memory until such time as the app is actually killed by the system. Merely going back to the home screen isn't good enough, since apps stay suspended in the background until the OS decides it needs that memory back. And if you have any 32-bit apps that actually do background processing, you'll end up with 32-bit apps in the background frequently.
Less than half as 32b code objects will be smaller than 64b ones, but even if it's half how much storage is that exactly? I mean I probably have games bigger than the frameworks on my device.
> As for speedup/memory gain, merely launching a 32-bit app will cause the OS to get a bit slower / use more memory until such time as the app is actually killed by the system.
Well yeah so it's just pay for what you use aka who gives a shit.
> And if you have any 32-bit apps that actually do background processing
Which is unlikely given the vast majority of applications being killed by this move are games.
I mean let's be honest for once, the gain from removing 32b frameworks is pretty much entirely on Apple's side, there's little gain to be found for end users when they're not just plain losing value in this move.
I've given you multiple concrete benefits to end users. You may not personally care about the code size difference, and you seem to be completely discounting the speed / memory usage issues, but just because you personally don't think those are a big deal doesn't mean they don't actually exist.
There are not benefits since they break software. You can get pretty much all of these by just removing remaining 32b software from your system.
1) Just removing all 32-bit apps doesn't recover the disk space used by the 32-bit versions of frameworks, and
2) If you remove all 32-bit apps, then there's literally no point to retaining the 32-bit OS support anyway.
That said, they force developers to discontinue support for old iOS versions, so if you don't upgrade, you'll stuck with old apps and some might stop work if they rely on remote servers with changed protocols. So if you want to use iPhones, be prepared to buy new phone every 3-4 years.
But if your device is a few years old… You're right that you may want to wait and see what the reviews say. Sometimes the updates actually make the phone feel faster, but sometimes (like iOS 7 with all the new transparency effects) it definitely can be a worse experience.
You can target at least back to iOS 7 (https://forums.developer.apple.com/thread/50410) that gives you support for phones back to the 2010 iPhone 4.
Apple also will allow you to download an older version of an app if the newest version doesn't support your hardware. I can confirm that this works back to devices that only support iOS 5 - like my first generation iPad from 2010.