Some of you people need to seriously understand the difference between this and iTunes Radio. I am so tired of people spewing wrong information or bashing Google just because it's a Google App. First things first,
-Google Music is a FREE cloud storage for your local music. It is akin to iTunes Match, except it is free and lets you access you music in a browser or Android/iOS device. It even plays nicely with iTunes. Once you set up the music manager it will automatically scan your iTunes library and upload all the music. Any changes you make later down the road will also be uploaded.
-Google Music All Access is Google's subscription service that is $9.99 (or $7.99 if you signed up early) and is akin to Rdio, Spotify, or MOG. It is not a competitor to iTunes Radio although it does have a Radio feature like Pandora or iTunes Radio. Basically, All Access gives you access to stream any song that is available in the Google Play Store at any time ad-free. It also lets you add albums or songs to your library of uploaded music so it is all in one place. If you unsubscribe obviously all the music you added that wasn't your own will disappear. It also has recommendations like Rdio that shows you music you may be interested in. The Android/iOS app will let you download music to your device whether it is your own music or All Access music. You just go into the album and there will be a small orange downward arrow. Tap it to "Pin" the music locally on your device. You can try All Access for a month for free.
So as you can see these two services are completely different. iTunes Match is nice for local music but it cost $25 a year and will only let you access you music from an Apple Device. iTunes Radio is simply Pandora that has access to all the music available on iTunes. It doesn't let you pick what song you want to listen to. It just generates playlists based off an Artist, Album, or Song. It let's you skip songs a few times and it has ads unless you have iTune s Match. If you are someone who just flips on a radio playlist then yes, iTunes Radio is nice. But if you are someone who wants to listen to a specific song or album at any times, wants to build playlists, etc. then obviously you want a subscription service such as All Access, Rdio, Spotify, or MOG. If you want that but you only listen to music on your computer then you can probably suffice with Spotify's free service. If you want all that music on the go then you will have to pay monthly.