A Google Play Music update v5.2 just popped up in the Play Store, though it's being slowly rolled out, as is the case with many big Google apps nowadays. The previous version is 5.1, and indeed I'm seeing quite a few changes inside that would warrant a point release.

Update 9/10/13 4:00pm PT: the official changelog has been posted:

What's New v5.2.1204L * All Access Genre Radio is here! Go to Radio or Explore, pick your favorite genre and enjoy unlimited radio based on the music you love. * New download queue that allows pausing, resuming and cancelling

Genre Radio

A detailed teardown may be coming in the future, but in the meantime, there is one big change that was immediately apparent: Google Play Music now supports Genre Radio in addition to the regular artist/song radio. You need All Access for this. Genre Radio appears as a new tab under Radio and looks like this:

Left: Play Music 5.1; Right: Play Music 5.2

The genre radio actually shows you sub-genres first, so you can start either the topmost genre or the sub-genre of your choosing:

Send Feedback

In addition to the genre radio, I've spotted a new Send feedback button:

These are all the major changes I'm ready to report right now, pending Google's own changelog and our full teardown. There is a lot of activity regarding downloading/pinning/removing music, but I'll have to dig into those deeper before figuring out what's new.

Download Queue UI

Update: Yup, there is now a proper Download Queue UI for downloading/pinning music which finally supports a Pause/Resume button:

Left: Play Music 5.1; Right: Play Music 5.2

Left: Play Music 5.1; Right: Play Music 5.2

APK Download

Thanks, +Tommy Nunno and Keyan X!

P.S. The Download to SD card hack that was removed in the last update is still gone.