I had a G3 and I really liked it, not many complaints other than battery life was average. Then I switched to an S6, had it for a couple of months and ended up selling it. Even though the screen and camera were impressive, battery life just wasn't good enough for my needs, it made me so paranoid if I had to go out and the phone wasn't fully charged.
So before selling my s6 I did a lot of research (this was about a month ago) and I read a lot about the Z3 and Z3+. Ended up getting the Z3 because I didn't see any real upgrade on the Z3+ and besides I saw a lot of overheating complaints due to the 810.
And I have to say I absolutely LOVE this phone. I have no complaints whatsoever. Some people have complained about the camera but so far I've had no problem with it, it takes great pics for me. UI is basically stock Android, buttery smooth and the battery life is the best I've ever had on a phone. I don't usually let the battery drain completely, but in the beginning I did just to see how much I could get out of it and I easily got over 8 hours of SOT with 2 full days of usage. So safe to say I was truly impressed.
As far as the screen, it's very bright, indoors I usually have it at about 25% and outdoors I slide it up to about 60%, maybe a little more if it's too sunny, but I've never needed to take it up to 100%.
I can't say if it's better than the G4 or not because I've never had the G4, although I don't doubt it's a really good phone since I liked the G3. So I can just tell you about my experience with the Z3, so far no regrets at all
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