I've been checking out the beta of this and so far I like it. (I've been doing the trial of Rhapsody at the same time).
I like that Yahoo has a plugin architecture that allows for a certain amount of user input and customization. There's a great plugin to subscribe to podcasts and spider MP3s from websites (which is great 'cause I download from a lot of old vinyl sites--http://www.weirdomusic.com/downloads.htm) I also like the ease with which you can rate artists/albums/songs.
The software seems a bit slow and there doesn't seem to be as great a variety of albums as Rhapsody (but they are in beta, so...). I do, however, like the pricing. $5 a month is pretty awesome.
I was curious as to whether these services might be some day available within MC like CDBaby and AudioLunchbox. If so, then this would be SWEET!!!! The less applications I have to use, the better.
Brad