iOS 10.3
https://www.macrumors.com/2017/03/27/apple-releases-ios-10-3/
macOS 10.12.4
https://www.macrumors.com/2017/03/27/apple-releases-macos-sierra-10-12-4/
watchOS 3.2
https://www.macrumors.com/2017/03/27/apple-releases-watchos-3-2/
tvOS 10.2
https://www.macrumors.com/2017/03/27/apple-releases-tvos-10-2/
As a major 10.x update, iOS 10.3 includes both significant additions and more minor design tweaks and changes. The biggest new consuming-facing feature is "Find My AirPods," which has been added to the Find My iPhone function to help AirPods owners locate a lost earphone should one be misplaced.
Find My AirPods can play a sound to help users find an AirPod misplaced nearby, and it also saves the last known location of when an AirPod was connected to an iOS device via Bluetooth, but it can't locate the AirPods when the iPhone isn't nearby nor can it locate the Charging Case.
iOS 10.3 introduces a new Apple File System (APFS), which is installed when an iOS device is updated. APFS is optimized for flash/SSD storage and includes improved support for encryption. Other features include snapshots for freezing the state of a file system (better for backups), space sharing, and better space efficiency, all of which should result in a more stable platform. Customers updating to iOS 10.3 should first make a backup given that the update installs a new file system.
Some App Store changes are coming in iOS 10.3, allowing developers to respond to customer reviews for the first time. iOS users are also able to label reviews in the App Store as "Helpful" or "Not Helpful" for surfacing more relevant review content, and Apple plans to limit the number of times developers can ask for a review. The update even adds a master switch that lets customers turn off app review request prompts all together.
Other new features in iOS 10.3 include a revamped open/close animation for apps, an Apple ID profile in Settings, a better breakdown of iCloud storage usage, warnings about outdated apps that may not work with future versions of iOS and could slow down devices, HomeKit support for programmable light switches, improvements to SiriKit (bill paying, bill status, and scheduling future rides), CarPlay interface improvements, and iCloud analytics options.
https://www.macrumors.com/2017/03/27/apple-releases-ios-10-3/
macOS 10.12.4
macOS Sierra 10.12.4 brings iOS's Night Shift mode to the Mac for the first time. Night Shift, first introduced on iOS devices in iOS 9.3, is designed to gradually shift the display of a device from blue to a subtle yellow, cutting down on exposure to blue light. Blue light is believed to interrupt the circadian rhythm, disrupting sleep patterns.
The 10.12.4 update focuses primarily on Night Shift, but the update also includes dictation support for Shanghainese, cricket score integration for Siri, improved PDFKit APIs, and new iCloud Analytics options.
https://www.macrumors.com/2017/03/27/apple-releases-macos-sierra-10-12-4/
watchOS 3.2
watchOS 3.2 introduces Theater Mode, which is designed to let Apple Watch owners mute the sound on their device and disable Raise to Wake, preventing the screen from lighting up with arm movement.
Apple Watch users are still able to receive haptic feedback-based notifications, and incoming information can be viewed by pressing down on the Digital Crown or tapping on the screen.
The update also brings SiriKit to the Apple Watch, letting users ask Siri to do things like send messages, send payments, book a ride, log a workout, make a call, or search through photos. SiriKit has been available on iOS devices since the release of iOS 10, but is new to the Apple Watch.
https://www.macrumors.com/2017/03/27/apple-releases-watchos-3-2/
tvOS 10.2
According to Apple's beta release notes, tvOS 10.2 introduces improved scrolling behavior, allowing tvOS users to scroll through large lists of information more quickly. A longer swipe on the Siri remote activates the new scrolling mode, and a swipe on the right side of the remote allows users to navigate specific indexes.
While Apple's release information only focused on the new scrolling mode, the update also likely includes other small feature tweaks under-the-hood bug fixes and performance improvements.
https://www.macrumors.com/2017/03/27/apple-releases-tvos-10-2/