I find this to be one of those things in life where people with negative experiences are just significantly louder than people with positive ones. It's like hunting for an apartment - you're only going to find bad reviews, because when something works as expected people don't usually feel the need to praise it.
I've had a generally rock solid experience with iOS11 so far (and I have a 6+ with a degraded battery to boot - things still operate fine, never needed to reinstall fresh or anything).
I _will_ say that Tinder has a huge issue in their app, where whatever the hell they're doing in the background balloons out of control and seems to cause some kind of memory pressure on the device. I don't use Snapchat so I can't comment if it's the same issue there, but on my phone it's Tinder-specific: literally no other app has this issue, but the simple act of opening Tinder and swiping through a few will cause the device to go crazy and silently kill other apps in the background for some reason.
I originally thought this was just my 6+ (i.e, maybe the degraded battery or something), but I've tried it on some development devices I have and it exhibits the same thing for me. My best guess is that the crowd that uses Tinder is willing to ignore that kind of issue because... well, it's Tinder, people are on there for a reason.
Re: wifi/bluetooth, I actually vastly prefer the way it is now. It took some getting used to but it just makes more sense.
Of course, your mileage and experiences may vary, so what do I know.