Just got this by mail
This is actually different. It is not a spotify or Rdio clone ... the idea behind this is only a
PlayDoctor type streaming API that opens up via a boom box icon when you are checking out an artist. But it uses Allmusic's enormous metadata and related artists libraries, to put together a playlist that is pretty darn good compared to the Artist that you originally typed in, so its more about discovering similar stuff than listening to a particular artist. Some of the indie music I listen to doesn't work, but you can get pretty obscur and even if they don't have music by the artist available, you can get related artists which is really why your listening to this in the first place.
These are not 30 second clips, so for their API to work you have to turn off AdBlocker if you have the extension installed. You can skip only 6 songs per hour, but there are no bothersome audio ads like Spotify free (at least in europe). If you are interested in skipping around, just pick a new artist or click on the boombox again.
Interesting to see what happens with this as they have also, like IMDB, have allowed you to create lists, and since two weeks ago you can now share those lists. As it just started, some things are lacking like linking back to other artists pages, but I'm sure that will come. When they come out with the mobile version this would be pretty engaging ... if it stays free that is.