I got the G Flex specifically because it was curved. But it was impossible to use one handed. The video quality was really great, but the picture quality not so much.
It also had the "self healing back", but the protective plastic coating that made it so was really thin.. And not really -that- self healing. The coating got scratched off entirely in a couple of places. Also there was only like 1 case even available for it and it wasn't handy at all So I never used it.
The G3 is really lightweight and thin- defo had to buy an otter box for it to add some weight and thickness to it. Plus I dropped my G Flex and busted the screen so yeah. Needed that. But the image & video quality, like I said, are amazing. And the sound ain't bad either. It's no Harmon/Kardon like the HTC One, but it does its job.