Well.... I am not making the switch... but my WIFE is.
And I just got my shipping notice from T-Mobile that her S7 is going to be arriving tomorrow, in which case I'll take it out for a shakedown cruise before I hand it over to her. Her current complaints with her G4 is as such:
It's a bit too big. She runs and has it in a wallet case with one of those strappy things on the back to make it easy to hold. She wanted something smaller, didn't hesitate to say so.
The battery life on the G4 is kind of junk. She'll average about 3 to 3.5h of screen time over a 24 hour cycle. Not exactly heavy usage either. And if she started to actually beat on it? Whoa nelly... we were in Disney recently and her G4 would burn through batteries like no one's business. Around dinner, my 6P would be sitting there around 50% while I already swapped out her battery... twice.... She wasn't all that happy with that. Those battery tests that have popped up aside (those battery benchmarks are fertilizer btw... I put ZERO stock on any of them).... I expect the S7 to outpace the G4 by a fair margin, at least enough for it to make an appreciable difference for her.
And while the G4 camera was really good, it had its issues. For whatever reason, every so often it would focus like a stoned college student... especially indoors and in darker conditions. She'd take a pic and it would just go out to lunch for several seconds before taking the picture. She's complained to me, several times, about the focus wonk and I've verified that... seen it in action... Not pretty.
One thing I've noticed is that the G4 pictures look a lot better on the camera than on a larger screen. Up close, pixel level, its over-processed... the famous 'oil paint' look. I've found that the pictures I get from the 6P are a lot more detailed and fine when you look down deep, and that results in a much crisper, sharper full image. This isn't just a couple... we've taken hundreds, if not thousands of pictures back and forth between both phones over the past few months.... 6P wins, every time. Big sensors FTW and all that. The shots I saw of the S7 and G5 (which has the same sensor as the G4) showed what I thought they would... the same muddy pixel level detail on the G5 and the S7 and its larger sensor is clearer.
So I'm in the same boat... and, for me, the S7 was a worthy enough upgrade as it checked all those boxes. Though, I am having a few doubts.... I mean, if the latest update fixes the performance issues with the Nexus 5X.... the current Fi promo.... I could stand to save about $120 this year, $480 year two.... if the Nexus 5X runs reliable enough to not annoy her. But that's a topic for a different day.