Done the update.
Looks the same.
Feels the same.
It's the same.
Seeing as I wasn't going to delete a few GB of MY data to do the upgrade, I entrusted it to the magic of iTunes.
I upgraded iTunes, made a full backup of the phone and then performed the upgrade. Took all of 15 minutes, and not a single problem (yet).
Not that it seems to have done anything. I've already turned off the 'next predicted word' feature on messaging and e-mail. It's never worked (on any platform) and will never work, EVER. I am not Stephen Hawking, I do not talk in sentences predetermined by a computer.
The 'Recent' contacts at the top of the screen are annoying.
I like that I can share paid apps between 6 devices, even with different Apple ID's.
Camera 'upgrades' are a waste of time, the camera is shit and will remain shit.
Still won't own a Samsung though!