I've had mine for a little over a month. I can't really find anything negative to say about it. Coming from a Nexus 6 -- a phone I consider to be THE best in the Nexus line -- I was afraid anything else would be a compromise. I don't feel that way today.
I have no issues with the 18:9 format and truthfully, even though the screen is a little smaller than the N6, it doesn't look that way, especially since the pixel density is much higher. I'm not doing anything fancy with the color temperature of the display, just basic default settings at a medium-high brightness level.
The phone is much more holdable and pocketable than the N6 was (both in cases). Out of the case the N6 ... and the S8 ... feel great in your hand, but those are both phones that to mee are much more droppable, so a case isn't really an option there. The G6 could live without a case pretty well and I might go there eventually, but I've gotten used to the clear slim cases so I'm sporting one of those now.
I'm finding the wide/normal lenses to be much more useful than I ever thought I would. It's not Instagram material, but when I need to take pictures of the back of a server or switch in a tight rack, the wide angle has been a godsend. And, I do agree, Joe, that Samsung does way too much post processing. Do they even have an option to capture RAW? The G6 does.
Battery life has not been an issue. I have wireless chargers at my desk at both work and home and just set it there so I almost never have a charge lower than 80%.