El Capitan is officially here! The App Store front page and Apple’s website have yet to be updated, but as Jason Snell tweeted, El Capitan is now available on the Mac App Store. Here’s the App Store link.
It’s unclear at the moment as to whether the final build is different than the GM Candidate build that Public Beta testers received a few weeks back.
Before you update, be sure to back up your system, just in case something goes wrong. And as usual, some apps may stop working upon upgrading: This may be a bigger issue this year given some underlying changes to OS X that may break some apps, as Ars Technica notes. If in doubt, wait a few weeks for the dust to settle.