I got the G4 very soon after it came out.
It's funny, I was getting frustrated with it but this past week or so, it's suddenly really grown on me!
LG have already released a couple of software patches that have improved performance, and I'm hardly getting any lag at all (that's also using an SD card). The camera seems to be the best all-rounder there is, especially after seeing the shootout on Android Central between the S6, the G4 and the OnePlus 2.
I actually got an S6 Edge when it came out, and thought that it was fantastic. I just didn't like certain stuff, like the glass back (which in my house, would get destroyed in 10 minutes lol). But Samsung generally did a great job indeed. The thing is the S6 is essentially Samsung's (advanced) version of an iPhone 6.
The LG G4 is "ANDROID" through and through. There's SD card support, removable battery, it's customisable, you can throw it around without worrying it will shatter, it's got a large beautiful screen but a compact body, it's very light compared to similar phones, it's "only" got an 808 but flies (that 3GB RAM helps)....
I dunno, the OP is pretty much spot on. I look at a Nexus device and can only see it adding a couple of things, like fingerprint scanner and being pure Android.
The other thing - the price on a G4 is insane, you can now easily pick one up for £300-325 which is SUCH good value. Tbh the Moto X Style won't be that wildly different. The G4 bodies the iPhone 6 Plus is almost every way, it's just missing a fingerprint scanner. Apple will need to do well with the 6S range.
The G3 was exactly the same experience last year - first couple of months, hmmmm... Then LG every 6 weeks would fix so much stuff that it changed the user experience. It even got a solid build of Lollipop on DAY ONE, even before some Nexus devices!
Honestly, LG are making a lot of good decisions and phones. They are not perfect, but they are without doubt the best all-rounders you can get. I've been eyeing up so many phones, but when it comes down to it (so far) none of them would make me trade in my G4.