The promise of Google Music is that it lets you listen to music anywhere. Aces! Except, for all the unifying promises of its online locker, Google Music does kinda the same thing as your hard drive: it isolates your songs.
It's basically the Skull Island of music services.
You know how it works: You take the music you already own and upload it to the web where you can get at it from your phone or browser. Essentially, you're taking the island of music on your computer and dropping it in the cloud.
But it's still an island. It's still a self-contained unit. You have to manage it yourself. It won't grow unless you manually add tracks to it. There's no serendipitous discovery. No social component. No Pandora or Last.fm-style suggestions that drop tracks you've never heard before, but already love. Google isn't offering you a vast, new catalogue. It's just offering to hold your shit for you.
You know what would have been a really exciting announcement? If Google announced that it was finally commoditising music. That - not some online tune ghetto - is the next step for music services. That's the leap we need to make.
Consider NavTeq. Garmin, Magellin, Yahoo Maps, Mapquest, Lowrence, and even XM Radio all rely on the same NavTeq data set. Garmin and Magellin can set themselves apart with pricing, features and form factors, even though both use the same basic commodity to deliver what users ultimately want.
At some point in the future music services - like Rdio and Spotify and likely iTunes and God help me even fucking Rhapsody - will likely be completely commoditised. They'll all have the same catalogue, but will differentiate themselves by their discovery, sharing, interface and delivery features.
I don't want another place to simply store songs. I don't want to be isolated. I want to connect with new albums and people and artists. I don't want to just move from one island to another. I'm ready to be rescued.
*Assuming your library fits in Google or Amazon's locker. If it's too big, you're still going to have to keep some of it on that island in your desktop.