Right from the off, you'll notice a change. The lockscreen has been redesigned, adding rich messages, interactive live status updates with apps such as Uber, and shortcuts so that you can quickly access the camera and music apps.
Meanwhile, on the homescreen, widgets are being upgraded and 3D touch provides more information for selected apps, including Apple's own activity app.
One of the biggest improvements with iOS 10 is Siri. Apple's virtual assistant has been opened up to developers, so you'll be able to ask her to work with specific apps. Federighi demoed Siri by saying, “Tell Nancy I’ll be five minutes late with WeChat." She can also work with apps like Uber and Lyft, and various workout apps.
Apple has overhauled its Messages app; emojis are now three times bigger and the app will even offer predictive emoji. This allows semi-autonomous replacement of words with emoji.
Meanwhile, typing something like "Congratulations," or "Happy Birthday" will prompt animations to take over the screen.
There's also a clever time saver feature called Tapback, which lets you send one of six quick responses.
Apple Photos has added facial, scene, and object recognition, and you can view your photos on a map. The app will also group photos based on trips, people, and activities, in what Apple calls "Memories."
The final version of iOS 10 is expected to be released in September.