At this point my choice of music service boils down to which one will let me store all my music in the cloud for the least amount of money... and actually work long enough to play it (lookin' at you, Google Play Music). So, Amazon Music and the Prime service it's associated with are looking more attractive these days. If you're one of the very few early adopters of Android Auto, you can now use the app with Google's vehicular electronics system.
The Amazon Music app has also been updated with more functionality for the Prime music stations that were added earlier this year. Specifically, the update adds the station to search results within the app itself. (Which might be a bit of a bummer if you don't like the stations, but oh well.) The in-app search function also includes results that appear as you type. Other than that, it's the usual bug fixes and performance improvements.