Picked this up yesterday. Watched 2 4k HDR movies and played a fair bit of Forza 7 in HDR.
Everything about the TV is amazing, except it has some backlight bleed (minor) and the uniformity is pretty bad. HDR on the other hand is absolutely mind-blowing and the colors are fantastic. This is the only TV aside from an OLED that gave me the 'colors pop right out of the screen' feeling. Not sure how much HDR has to do with that though.
Example of poor screen uniformity:
When racing around in Forza, the top half of the screen is usually a relatively solid gray/blue from the sky. When taking quick turns, I can definitely see little hazy patches or blotches that stay in place while the sky zooms around on the screen. This shouldn't be confused with actual fog or clouds in the sky (even though the effect may be similar). It is just poor screen uniformity that causes this effect.
Important note about screen uniformity:
I found that if you dial down the 'backlight' to around 20-30 in HDR, the 'blotchyness' from poor screen uniformity is drastically reduced. This also lessens the HDR effect though, so it's a trade off.
If it wasn't for the poor uniformity, I would 100% be in love with the P607. At the price I paid for the P607 (and the extra cost of upgrading to an LG B7 OLED), it's extremely hard to justify the upgrading to an OLED. Also, just sticking with my old TV until OLED prices come down more is still an option as well. Speaking of my old TV, I feel like I got extremely lucky with it. It has absolutely zero backlight bleed and screen uniformity is probably the best you can get with a budget TV. Not sure what I am going to do at this point. I will probably give it a week or so and see how I feel after more time with it. The poor screen uniformity really bothers me, but at the same time, it would be really hard to go back to my non-HDR set. HDR is an absolute game changer and looks really stunning.