Well, I listened through iTunes 11 to several albums last night, and I think it sounds better than ever- and the new interface is both awesome and weird. ;)
Need to listen a lot more to determine how it fares against Amarra and the like, but initially at least, it seems to stand up pretty well.
It is finding stuff that isn't an exact match in iTunes Match and presenting it along with the local full resolution files. Have to figure out how to tell it to ignore that function. I do like the iTunes match for when I am in the truck. Can't beat being able to listen to a big chunk of your library, even at 256kbs AAC. I can say that works well with the new iTunes 11 as well. I RIPed a disc in last night, and it was available in the truck this morning.
i agree with you paul this is the best sounding itunes so far.