It's been a good while coming but Google's music streaming service has finally arrived. Called Music Beta, it's available by invitation only and restricted to U.S. users ahead of roll-out elsewhere. The service appears to be very similar to Amazon's Cloud Storage and Player, although no music is on sale directly from Google. Rather than measure the size of your collection by the gigabyte, however, Google will allow users to store up to 20,000 music tracks from their personal collection in an online vault, with no restrictions on bitrate. Music Beta offers users instant sync across devices, the ability to play selected music offline and intuitive playlist creation based on the mood of a selected track.

Google says that so long as the Beta tag remains, its Music service will be free to use. There's no indication at the moment when subscribers will be expected to pay for the service or how much it will cost, but Google has a history of keeping Beta tags in place for a good while and its track record in online storage would hint at the lower end of the cost scale.

Like the rather disappointing Music Search before it, the new service is initially being made available to U.S. users only, those wanting to take it for a spin will need to apply for an invitation. Users elsewhere in the world will have to wait for a staged roll-out.

Once the invitation is secured, you'll need to get your music collection from your computer to your online library via a Windows and Mac compatible Music Manager application. The service is limited to MP3, AAC, WMA and FLAC file formats which may cause some issues for old iDevice users and lovers of other formats like OGG and APE.

Google's choice to automate much of the management rather than allow users to get their hands under the hood will no doubt be welcomed by those wanting quick, painless access, but is not so good for control freaks or power music managers.

With the cloud library positively brimming with uploaded content, users can then access tunes through a web browser or up to eight devices running a dedicated Android app available for free (at the moment) download from Android Market.

As everything's stored in the cloud, the service offers instant sync between devices - so if you create a playlist on your home computer, it will be available straight away on your mobile device. If you have neither the time or the patience to create playlists then Music Beta offers to do it for you. Instant Mix will draw together 25 similar music tracks from your collection based on a chosen song to rock you hard or chill you out.

In theory at least, having your music collection available to you at all times sounds absolutely wonderful, but in reality such a service could quickly eat away at your monthly mobile allowance. To this end, Google has included the facility to manually select specific albums, artists or playlists or cache recently played music to play offline.

Although I feel that the new service is a welcome move in the right direction, Google will have to offer a lot more than this if it hopes to compete with Amazon's existing service and Apple's up and coming effort. Offering more user control for those that want it would be a good start, closely followed by catering for purchasing from within Music Beta itself.