Google still doesn't have a Play Music API for third-party apps, so I'm essentially forced to use the official app for streaming my music. If I had the option of using any music app and still getting my cloud tunes, I'd use Shuttle—we've even recommended it a few times. This app is feature-rich and has slick design, but it's getting even better today with a big update to v1.5. This is the second phase of the developer's material redesign, and it's looking great.
New 'support'; menu: Version info, e-mail me, link to the FAQ, donate button
Some major performance improvements
The centerpiece of this update is the material design makeover, which apparently took quite a few betas to get right. It seems to have been worth the wait, though. Shuttle shows off a very nice material interface with extremely granular control of themes and colors. The layout, use of the FAB, status bar, and animations all look right too. The nav drawer uses the older spinning arrow layout rather then the full-height drawer, but I can forgive that. Another update is in the works that will bring more animations to the app as well.
You can try Shuttle for free, then buy the $1.75 "plus" version if you like it. There's also a new option to simply upgrade the regular version via an in-app purchase.