Err could be
I have it switched off as basically what it does is suggest songs that would work well together in a playlist and ones you can buy from iTunes of course
However it does all of the processing server side so has to upload the catalogue to Apple's servers amd then retrieve the results.
Personally I think its a wate of time (and bandwidth) do have switched it off (if your library is large than I'd say the upload and download would be large too.
