According to Apple, the update:
- improves Wi-Fi reliability
- improves the reliability of Handoff and AirDrop
- fixes an issue that may cause Bluetooth devices to disconnect
- fixes an issue that prevented Mail from deleting messages in an offline Exchange account
- fixes an issue that prevented importing photos from an iPhone to a Mac using a USB cable, and
- improves iCloud Photo Sharing for Live Photos.
Apple also has a support page that details the security content of OS X El Capitan 10.11.2 and Security Update 2015-008.
Before installing the update, back up your Mac’s data. The update is available in the App Store under Updates. You can also go to the Apple menu, select About This Mac and click the Software Update button in the Overview window.
Developers, take note: Apple also released Xcode 7.2, which includes Swift 2.1.1 and SDKs for the OS updates that Apple released on Tuesday.