Given that the founders of RDIO come from Kazaa and Skype, it's no surprise that this subscription service has a very strong social networking focus. Although it doesn't have as big a library as the veterans of this group (roughly 7 million tracks), Rdio's social component lets anyone see who's listening to what and who's following whom. The interface makes it easy to find people to follow, and it's a cinch to post your latest spins to Facebook and Twitter.
Rdio offers unlimited on-demand access for web and mobile (streaming and downloads) for $9.99 per month, while web-only access costs $4.99 per month.
Another benefit of Rdio is that users can collaborate on playlists, which can be great for parties or other group activities. You also get personalized recommendations based on your listening habits, as well as on-demand artist channels and stations based on what's in heavy rotation on your profile or in your network of friends.
One standout feature is a tool in the desktop software that scans your iTunes or Windows Media Player libraries and matches them to the same tracks in Rdio's library and adds them to your virtual collection.
In our testing, this took several hours, and the service picked up 7,500 of our 30,000 songs. You can then access that music from your computer, Android, Blackberry, or iPhone. (Windows Phone 7 supports Rdio streams but not downloads.) Oddly, you can't use the mobile app to view your virtual collection, and the look and feel is pretty low-rent.
Click to enlargeThe desktop web interface is simple and easy to navigate, though we did find a few glitches, such as songs not showing up in our queue despite confirmation that we'd added them, or songs simply not playing. Your web queue gets synced with the queue in Rdio's mobile app and vice-versa, though it would be even cooler if the current song were also synced in the Now Playing window.
The Rdio mobile app has a fairly polished interface, but we were surprised that it doesn't capitalize more on the service's social component aside from letting you see friends' recent activity and listening history. For example, you can't search for new friends to follow or share specific songs with other users. The iPhone app crashed a few times during our testing, but the audio quality of the stream over Wi-Fi was the best of the bunch. Interestingly, the company claims both downloads and streaming is at the 256Kbps MP3 format regardless of whether the connection is over Wi-Fi or cellular; our ears easily verified this was not true on a iPhone 3G's connection, as the stream was compressed to what sounded like 64Kbps AAC+.
If you're already active on social networks (and aren't overwhelmed by them), and you're interested in learning about new music from friends, not strangers, Rdio is a great choice. If you're just about sheer catalog numbers, look to one of the other services.