tvOS 11.1 can be downloaded over the air through the Settings app on the Apple TV by going to System --> Software Update. Apple TV owners who have automatic software updates turned on will be upgraded to tvOS 11.1 automatically.
tvOS 11.1 focuses primarily on bug fixes and performance improvements rather than outward-facing design changes, and no significant features were discovered over the course of the beta testing period.
The update does introduce a fix for a major vulnerability in the WPA2 Wi-Fi standard that protects many modern Wi-Fi networks. Many Apple devices had the potential to be impacted by the vulnerability, but it has been addressed in tvOS 11.1, iOS 11.1, watchOS 4.1, and macOS High Sierra 10.13.1.
tvOS 11 introduced features like full support for AirPods, automatic switching between light and dark mode based on local time, Home screen syncing options designed to keep multiple Apple TVs in a single household in sync, and new background modes and notification support.