I had it for a couple of days on my Air 2. Battery drained more quickly, but not terribly so.
But I went back to 8.3 because I couldn't post a photo to Facebook in the photos app, couldn't search my email, and my NY Times feed in the Pulse app crashed the app. No idea why. Macrumors feed crashed it too sometimes.
I also found myself missing swipe forward in Safari, which appears to be completely gone in lieu of the split screen swipe.