iOS 11.3 is a relatively large update that includes some new features, such as Messages in iCloud to synchronize messages across devices and conserve disk space.
In addition, iOS 11.3 includes numerous security updates, so it is recommended that you install the new version.
ARKit 1.5 adds the first revised version of ARKit, which debuted in iOS 11. The 1.5 version is able to more accurately map irregularly shaped surfaces, recognize images and place objects on vertical surfaces such as walls. Thus, e.g. Museums filled with interactive exhibits or a movie poster come to life. The real camera view when using AR provides 50 percent higher resolution (1080p) in ARKit 1.5 and supports autofocus.
In the Health App, Apple adds a new Health Records feature to it To facilitate customers with a participating medical facility to directly access their data in the iPhone, even if this medical information is distributed across multiple providers. Of course, this only happens with the consent of the user. So far, only US clinics in this cooperation.
Who has an iPhone X, can look forward to four new Animoji. Below is a lion, a bear, a dragon and a talking skull. The update has only been released for the new iPad, but that may change soon.
In iOS 11.3, there are also battery health indicators and the ability to remove any system throttling. This only applies to iPhones - with iPads there was never the automatic throttling.
Actually, Apple wanted to realize in iOS 11 and AirPlay 2. The revised music transfer function should provide a more stable connection than before and allow multi-room audio, which should be driven straight through the HomePod. Apple's smart speaker should also use the feature to allow stereo playback across two connected devices. Unfortunately, Apple had already removed the function in the beta versions of iOS 11.3 quickly. The beta testers were not told what the reason was.
In the book iBooks, Apple had deleted the "i" from its name in the previous betas, but had reintroduced it since beta 4. Why Apple changed the course here has not been communicated so far.
iOS 11.3 is now ready to be updated with the iOS software update for installation - if you already own the new iPad. Why Apple released the update only for the new iPad is currently unclear.