Apple’s iOS 13 is available as of today, bugs and all. The Verge has a review.
The planned upgrade, iOS 13.1, will now be released on September 24th instead of the originally planned September 30th, six days ahead of the original schedule.
TechRepublic has an iOS 13 cheat sheet.
iPadOS is also launching September 24.
9to5Mac has a list of the iPhones and iPads that support iOS 13 and iPadOS 13