Some of the V30 review units apparently have display issues. Ron Amadeo of artstechnica.com https://arstechnica.com/gadgets/2017/09/lg-v30-hands-on-lgs-oled-displays-still-have-quality-issues/ states that the following as examples:
"In low brightness in a dark room, the screen is grainy and has "dirty" looking horizontal banding all over it. The light level is also woefully uneven, with hotspots blazing out of the left and right corners."
"Notice how the Galaxy S8 produces a smooth, consistent color from the top of the display to the bottom. The LG V30 is supposed to be displaying a solid color, but it's so uneven that it starts out dark grey at the top and transitions to a light grey at the bottom. There's also lots of horizontal lines present in the LG display that aren't in the Samsung. It just looks so much worse."
So, there's some hope that these issues can be chalked up to pre-production hardware & software. And there is hope that this isn't the same panel that's going on the XL.
On the other hand, some other reviews state that it looks great... so what do we do with that info?
"In low brightness in a dark room, the screen is grainy and has "dirty" looking horizontal banding all over it. The light level is also woefully uneven, with hotspots blazing out of the left and right corners."

"Notice how the Galaxy S8 produces a smooth, consistent color from the top of the display to the bottom. The LG V30 is supposed to be displaying a solid color, but it's so uneven that it starts out dark grey at the top and transitions to a light grey at the bottom. There's also lots of horizontal lines present in the LG display that aren't in the Samsung. It just looks so much worse."
So, there's some hope that these issues can be chalked up to pre-production hardware & software. And there is hope that this isn't the same panel that's going on the XL.
On the other hand, some other reviews state that it looks great... so what do we do with that info?