I wonder if they didn't want to do a Buzz in terms of making all your private information suddenly public, and might ease into features such as scrobbling over time. The amount of spam on there is probably their biggest problem at the moment. It is hard for me to objectively judge as my market segment isn't catered for at all in terms of features. It will be interesting to see what the rest of the population think of it. To me it feels far to much like it has been designed to drive consumption of 'popular' music and 'me too' buying.

EDIT: The top 10 pop chart artists all seem to have around 100k followers, will be interesting to see how it goes.