Android Wear is still a very new platform. While it is approaching it's one year birthday - as it was officially made available at Google I/O last year which was in June of 2014. It's still got a long way to go, and we're constantly seeing the platform evolve and get even better. The Android 5.1.1 update for Android Wear has brought plenty of new features and UI improvements, as well as WiFi support, so you can leave your phone at home.
One of the other cool new features in Android 5.1.1 for Android Wear happens to be the ability to browse through Google Play Music. Now, obviously, you can't browse through your whole library including the artists, albums, etc. - which you also can't do on Android Auto, mostly because neither platform is really built for that. Basically what you're doing here is browsing through music you've recently played. Whether that's albums, playlists, songs or radio stations. So if you're looking for a song you haven't listed to in a few months, you'll need to pull out your phone still. Or use Voice Commands if you know the name of that song.
So far the Android 5.1.1 update is only available on the LG Watch Urbane and the ASUS Zenwatch - which not a whole lot of Zenwatch owners have gotten the OTA just yet. We should be seeing it heading to the Moto 360, LG G Watch, LG G Watch R, Samsung Gear Live and Sony Smartwatch 3 fairly soon. Of course, as soon as those updates decide to roll out, we'll be sure to let everyone know so they can smash that "Check for Update" button on their watch, or simply sideload it.
The browse feature here in Google Play Music will likely make its way to other apps on Android Wear soon, and perhaps after Google I/O. I think it would work great with other audio apps like Spotify, Rdio, Pocket Casts, Stitcher and the many other apps available out there. Hopefully Google doesn't let Android Wear do too much, so that it doesn't turn into just another display on your wrist, even though that's basically what it is these days.