Let's get the big one out of the way first: iOS 11.3 will now show your current battery health, and even recommended if your battery needs to be serviced. This is an upgrade from the current battery metrics available, which only include percentage of battery life remaining, the ability to enable Low Power mode, and battery usage (on a per-app basis).
These new settings will be available on iPhone 6 and newer devices. "Additionally, users can now see if the power management feature that dynamically manages maximum performance to prevent unexpected shutdowns, first introduced in iOS 10.2.1, is on and can choose to turn it off," Apple explains.
Other features coming in iOS 11.3 include some upgrades to ARKit, which was first introduced in iOS 11. ARKit 1.5 brings the ability to place virtual objects on vertical surfaces (i.e. doors and walls), and has improved algorithms to better map circular or irregularly-shaped surfaces.
"Using advanced computer vision techniques to find and recognize the position of 2D images such as signs, posters, and artwork, ARKit can integrate these real-world images into AR experiences such as filling a museum with interactive exhibits or bringing a movie poster to life," Apple adds. "The view of the real world through the camera now has 50 percent greater resolution and supports auto-focus for an even sharper perspective."
Another new feature coming to iOS 11.3 is the inclusion of your personal health records directly into the current Health app. You'll be able to view your medical records from "participating medical institutions" and receive notifications regarding labs results and medications, for example. Access to these records is of course encrypted, and protected with your device passcode.
Other odds and ends include new Animojis (including a bear, lion, skull and dragon), music video integration with Apple Music, and support for Advanced Mobile Location to provide to provide more accurate location data to emergency services.
The first beta for iOS 11.3 was released today, and the official release is reportedly coming in March.