Apple released iOS 9.0.1 just under an hour ago for all compatible iDevices with the following release notes:

This update contains bug fixes including:

– Fixes an issue where some users could not complete setup assistant after updating
– Fixes an issue where sometimes alarms and timers could fail to play
– Fixes an issue in Safari and Photos where pausing video could cause the paused frame to appear distorted
– Fixes an issue where some users with a custom APN setup via a profile would lose cellular data

For information on the security content of this update, please visit this website:
http://support.apple.com/kb/HT1222

No mention, however, about other bugs that many users have encountered since updating to iOS 9.