The service has been in beta since this summer. New features include the ability to purchase songs right from the online music player, deeper integration with Android devices and content partnerships. A new feature called the Artists Hub creates a market place for unsigned musicians.
If the Google Music catches on, it will certainly give iTunes and Spotify some competition. The service works by uploading your music to the cloud. You can access your library on the web via the Google Music homepage.
CNET's Greg Sandoval points out Google Music's shortcomings, which include the lack of a deal with Warner Music Group. Google does have a deal with the three other major U.S. labels - Sony, EMI and Universal Music Group. The search engine giant also has 1,000 smaller record labels onboard, which brings it's offerings up to about 13 million songs.
The only issue I encountered during the beta test is that depending on how much music you have, it could take weeks to upload your entire library. It took me about a month to sync 4,000 songs. However, that was on my laptop, which was only on for about three hours a day. The best part of the service is that it's free with no commercials.
Don't confuse Google Music with Spotify, though. They are two different types of services. You can't listen to anything that you haven't bought, unless someone shares it with you on Google+. It's probably more comparable to iTunes in the cloud.
The cool thing is that occasionally free songs are offered at the click of a button. It's an interesting way to discover random, but new music. I'm suddenly into Merle Haggard. It's the strangest thing.
It's definitely a good start and you can't beat a free service.