The AOD is the huge new feature. Nothing else matters this year.
It makes Series 5 a no-brainer purchase for pretty much everyone.
I am liking the always-on display very much - more than I expected to, actually. It was definitely a worthwhile upgrade from my 3-year-old Series 1.
But as much as I like it... I wouldn't have spent the money if I'd had a more recent version of the Watch. Replacing these devices every year or two just seems needlessly wasteful and irresponsible.