For me, I still have the issue where if I leave a video paused for a long time and then play it again, it often just hangs after resuming. And I can't press the stop or play button on Android to get it it moving again. But if I tap the progress bar, then I can "pause" it again (even though it's already stopped) and then press Play again and then it starts playing.
Also was playing a really long podcast tonight. And after playing fine for 40 minutes it stopped with the spinning circle, I assuming it's buffering, and after about 10 seconds it started playing again. The video was only 720p, and the wifi router is in the same room. It did that a second time on the same video about 10 minutes later too.
It's easy to use, but I seem to be running into a lot of quirks playing back YouTube videos with this so far.