Odd though, I've so far not had any problems with macOS Sierra on my Macbook Pro ... current uptime is a little over 12 days and no instability, no slowdowns, etc.
Generally I've not experienced any real issues with OS X for the last two or three revisions. Mail was a little flaky prior to El Capitan, but other than that no problems (although I don't use iTunes apart from transferring FLAC files to my phone, so that could explain things a little)...
Biting the hand that feeds IT
