So what does it really mean for the users ?
Google Music directly addresses some of the limitations imposed by iTunes. One of the limitations with iTunes is that a your music cant move around freely. If you are using iTunes to manage your music you can only do a hard wired transfer to your iPhones. Similarly if buy some music on iPhone and you want to transfer it to your PC you will have to use the same hard wired approach. Well, Google Music directly addresses these limitations. Once you have the music on to the Google's servers you can use it on any device that can connect to the internet.
Another limitation with iTunes was that if you are using Android phones and iTunes you will have to rely on third party applications to transfer the music to Android devices.Google Music provides an easier alternative to get your music on Android.
One thing you can't do with Google Music is to download the music libraries on another devices. Though music beta will allow you to download some music which you can listen to when you don't have internet connection.
You can now make a playlist on one device and have it available to all devices work or home !