JetPack is thoughtful collection of APIs along documentation, essentially providing solid guidelines on "how to write a modern android app". Good to see Google embarrassing Single Activity as well as reactive binding/view model patterns, and providing a standard way to implement it.
Then you have Auto.. I mean ConstraintLayout replacing all the other layouts, which is a good step forward too.
Android KTX looks good too, although it does seem to be a bit a odds with Anko? Or maybe not at odds, but looks like it has the same goal as Anko, to provide syntax sugar for Android Development in Kotlin. Could be interpreted as a "no" from Google in regards to Anko. As I really like Anko I wish there was more clear stance of what the future of Anko is.