Duo -- video calling, competitor to Skype? A "knock-knock" feature -- you see a preview of the caller before picking. Uses quic protocol, built by webrtc team, claims seamless transition when connections switch from wifi to cellular. Graceful degradation if network quality goes down.

Allo -- video chat, e2e encryption and expiring messages. That looks good but unless someone else audits, I'll be suspicious.

Android N -- Vulkan for games, that looks promising. New jit compiler, 75% faster app install speed, 50% reduction in size. File-based encryption. Seamless updates -- phone downloads system image in background. Then on next boot it switches to new image. Also split screen to see multiple windows at the same time. Those are some nice new features.