If the camera is really that important to you, I'd suggest trying it hands on yourself. Of all the negatives I've seen in the reviews, it's mostly subjective and easily compensated for in manual mode or so minor that you have to zoom in to the pixel level to tell any difference. All modern flagship phones have great cameras and software and the differences are very minor.
According to RaRa85, the V10 has rear curtain sync flash, so it's likely the V20 will as well. That alone opens up a lot more opportunities for camera tricks.even if slightly, does it seem an upgrade from the G4?
The sensor on the V20 is different from previous LG phones. It uses a different Sony lens and has a 4:3 native aspect ratio instead of 16:9. Also LG has gone to some lengths to add a third phase of autofocus detection to the V20 and the image stabilization is a nice leap ahead of the G4, G5, and V10 which had the wobbly effect. We'll have to wait until the detailed specs are released but it is a different Sony image sensor used for the V20. Also the only thing that separates the V20 from Samsung or the iPhone 7 is the auto imaging algorithms which means while the V20 will win some scenarios as proven by Android Central's blind camera test with pre-production software, in more settings Apple and Samsung's auto settings will be slightly better than LG's. Mostly in high dynamic range shots and certain low light scenes. With the manual mode, you can get shots noticeably better than in auto(if you know what you're doing/have the right set up). And the gap at the top of the pack in terms of image quality is not that wide anyway and unless you're going around comparing your photos to some stranger's or a friend, you won't be disappointed with the quality anyway.The camera is essentially the same as the G5. And if you're talking the 16mp primary, not only is it the same as the G5 but it's also the same as the V10 and G4. LG has been using basically the same camera sensor for almost 2 years now.