So far, there seem to be surprisingly few issues. Some glitches here and there, but overall stability looks still quite good. I would've expected major issues much sooner, especially as they did push out new features in the meantime.
Do you use it actively? There have been minor problems on a near daily basis and moderate ones a handful of times. It was only ever average stable before but it was at least always that, it's far less consistent recently.
Do you have data on this? Its not like other apps don't have issues. Sometimes I open netflix and it takes 30 seconds to show my profiles; that doesn't mean the app is garbage.
Do I have data on a website I use sometimes? No.
I use it actively and feel like recommendations have improved, at least for me. Ads are a bit more annoying but I've faced zero problems with stability. But I'm only reading, not actively tweeting.