I've been using Reaper since quite some time, and got accustomed to the default v5 theme. I liked it a lot for its clarity and simplicity. When the following major releases of Reaper came out, I've tried the new default themes but unfortunately I've never got to like em. I found them distracting and confusing.
I've tried a few 3rd party themes, but I liked them even less than the new defaults. Not to mention that more often than not they were also buggy.
Thus I always got back to the good old default v5 theme, although it's lacking the new features.
Eventually I found out about this one. From the screenshots I liked how it looks, and decided to try it out... and I've kept it.
It has a nice, modern and polished look, while not being distracting or confusing. Good job!
So far, the only defect I've found is that on a 2K screen the Theme Adjuster is practically unusable, as everything is so small that it's unreadable. Using the new "zoom" feature of Reaper does not help, either. The size of the theme itself get adjusted as expected, but the theme adjuster seems to be unaffected and its window contents remains minuscole. Not a big deal, but it would be nice to have that fixed, too. BTW, I'm on Linux. Don't know if that is a general problem or a platform-specific one.