Generally speaking, I'm happy with it. I have the AT&T version running 4.1.1. It is a huge step from my old iPhone 3G. The only quibbles are the battery drain (although I know how to get around it by rebooting), and a few minor bugs. On the lock screen, the yahoo news feed doesn't auto update on wifi altho on 4G LTE, and I can't get the camera to launch from the lock screen. Also, in bright sunlight, it's difficult to see the screen when taking pictures.
Call quality is good. I like Android OS, and it runs well on the hardware. Web surfing is pretty good. One strange thing is that when on wifi, some websites will hang and time out. When I turn off wifi and go to 4GLTE, I don't have that problem. It takes quite good pictures (sufficient for me).