It's worth mentioning though that there's often not a 100% feature parity between iOS versions on different devices, typically because of hardware changes. These even applies to devices of the same generation, e.g. iPhone 7 and iPhone 7 Plus have different camera features since the latter has two cameras and the former just has one.

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.

Thank you.

As a concrete example, iOS10 runs reasonably well on my spare iPhone 5, which is coming up on 6 years old.

However iOS11 won't be supported on iPhone 5 and earlier, i.e. on 32bit devices. Only iPhone 5s and up.

To put it into context - the iPhone 5 was in competition with the Galaxy S III and Galaxy Nexus at launch.

And my Galaxy Nexus stopped receiving updates 2-3 years ago despite it being a Google device (mine was also straight from the Google store, so it wasn't the carrier's fault).

Cyanogenmod supported the Galaxy Nexus until 13.0 which is Android 6.0.1. So Google just dropped support after 4.3 (coincidentally the last unsupported version) even though it was absolutely possible to update to newer versions of Android. As a result the Galaxy Nexus doesn't receive security updates from Google and is thus not usable as an online device.

if i recall the galaxy nexus was dropped just after 4.3, if i recall correctly this was due to Texas Instruments dropping out of the modem game no?

that was the last android phone I owned.

While iOS upgrades are usually free these days, it hasn't always been like this. According to wikipedia, iOS 1.1.3 was a paid upgrade on iPod Touches (while being a free upgrade for iPhones).

The first few upgrades were paid for tax reasons as far as I remember. And then after a few versions they were able to change that.

And only on the iPod touch, not on the iPhone. They also had to charge for a WiFi update on MacBooks for "accounting reasons".

Yeah I think the iPhone got around it because people were already paying monthly for it.

Yes, I remember that. I had to explain this to my parents so that they would let me use their Creditcard for this purpose.

iOS updates have always been free. There's no such thing as iOS 1.1.3, only iPhoneOS 1.1.3.

No they are right. Due to some sort of accounting thing once upon a time on some of the first iPod touches there would be a small fee to upgrade the OS.

Yes, and that was iPhoneOS, not iOS.