I have the display, a LG B9, and fill in card until the 30 series hits, 2060, but like others have mentioned, we don't have the outputs to really use it yet.
Slower paced games, ie- DQXI I run 4k 60Hz, anything else gets 1440p 120Hz. This display has GSync support so that helps with the fill in graphics power.
Visual quality... OLED versus LCD isn't a fight. Not really fair to compare, it crushes any LCD display so it's not a fair comparison.