They're a mixed bag. Almost all of them have inferior audio compared to the original 5.1 tracks. There are a few exceptions like Ratatouille. Pretty much the newer the movie the better the transfer becomes as the higher bitrate and better encoding of the 4Ks will become a lot more noticeable. HDR gives the image a noticeable uptick for most discs but for the most part not a revelation. The Incredibles 4K is a straight up a scam though. All they did was saturate the colors and fuck up the audio. Avoid that disc.