Had a LG G4 for a week, at the time when my LG G2's charging port was repaired.
When G2 was fixed, i decided to sell G4.
Apart from camera, it really didn't feel any better than G2. It wasn't faster, battery was worse, especially with full brightness. Screen quality is about same and 0,3" screen size difference was too negligible for me (I wan't bigger screen for my next phone).
Couldn't root/unlock bl without permanent loss of warranty. I was missing custom kernels and roms. G2 can have now same UX 4.0 UI, thanks to Cloudy.
Not that LG G4 is bad phone, but I'm going to wait Note 5 or some SD820 phone with 5.7-6.0" screen and over 3500mAh battery, before i update my G2.
G4 just didn't felt like a big upgrade over G2