it looks nice: but is sluggish (on my 2GHz PC)
if you use the library, don’t. it sucks. it seems to get the job done if you know how to use it but i find it a lot quicker to open My Music, and open songs that way.
the shuffle function – reminds me of 10 – doesn’t work properly. example: the playlist was All Music – it played song A,B,C,B,A. it would get stuck playing 10 songs in a loop – and i’m pretty confident that it guesses what you (don’t) want to listen to, by logging what you listen to and when. some might find this a nice feature but personally i hate it – random is random.

and it leaves clutter when you uninstall it – mp10 is never uninstalled, and the library from 10 is copied to 11 – but you uninstall 11, and you get the old library again.