As a developer this keynote was super interesting, but a little light on the technical details which have been present in years past.

watchOS - Better functionality and I really like the merging of glances and app launch screens, but I don't do any development here and I'm not sure if watchOS only needed polish vs. a full makeover.

tvOS - Unified login

was all I actually cared about seeing as a user, everything else is a happy surprise like slingTV finally coming to Apple TV (the Sling UI looked like garbage though) and Fox Sports. As an aside I've been tooling around with an App for this for one of my company's clients.

macOS - the Intelligent storage and the actionable Siri searches are interesting. Apple Pay for websites looks promising and I love the implementation of PIP. As a dev I wanted to see updates to the Mac app store (though I don't have anything there currently) and I was expecting the Apple Music refresh to extend to iTunes. Oh and that cross device copy and paste looks great as well.

iOS - The new and improved actionable notifications seem interesting and without a hands on the notifications, widget slide out, control center with home kit integration look like great improvements. I think I took iMessage a bit for granted as aesthetically it hadn't changed much since iOS 7, but the features and improvements actually look like dramatic improvements, though I am a bit disappointed that there is no Android port, but the potential add-ons that can be sold through iMessage could make it a profitable freemium app there.

Integrating third party development into Siri is absolutely massive to compete with Alexa, but Siri has several advantages that Apple looks to be cleverly leveraging: developer base, language support (Alexa only supports English), and multiple regions (Amazon Echo only works in the US). In addition, I really like the concept of using Maps, Photos, and iMessage as development platforms where smaller apps or promotional plug-ins that would be lost in the app store can be curated.

TL;DR There were a ton of little features announced that seem promising or are at least good attempts at catching up where other apps/services/platforms had distinct advantages.