Well i pickd up the LG G2 today. I have to say that this is one og the best phones I have had. To my surprise...the buttons on the back have not been an issue for me so far. The knock on the screen feature to turn the screen off nd to wake the phone is so useful. The camera is every bit as good as my S4.
The phone is very fast with no lag or stutter at all. The UI skin LG uses is very nice. I usually install Nova on my android phones. But i don't feel the need to do that with the LG G2. I can't comment on the battery yet...it has only been a few hours. I dd get the wireless charging unit as well.
Phonedog (Aaron Baker) loves the buttons on the back in his comparison to the HTC One
http://www.phonedog.com/products/lg-g2/
I am impressed with my first LG phone. It will become my daily driver if the battery lasts a day of normal for me use.....