Yeah, I have been using it on my 2018 4K tv since its launch on March 22,2019. The app has some bugs but not a deal breaker.
Bugs like sometimes it fails to start due to server time mismatch and you have to click on retry once and it starts just fine, the other is no subtitles in the big bang theory.
Rest all is good, picture quality is superb , much better than the firestick that I was using earlier. Interface is basically the same.
make sure you are on the latest webOS version. Below 3.5 is not compatible as of now.
EDIT - This has happened the first time yesterday night ,the app has stopped playing anything at all. Server Error. Unable to generate security certificate.
A lot of people have been facing problems, but i was lucky enough to get away with just an app restart but not today.
Hotstar is the worst.