For anyone here who is interested in the hi-fi audio experience and may be getting caught up in the debate over higher sampling rates and bit-depths, I'd like to suggest that any improvement Apple's hi-res audio is going to offer in sonic quality is nothing compared to the benefits of treating the acoustics in your listening space. Or conversely the destructive effects of NOT treating your room.
In an untreated room, moving your head to the side by a few inches will have a far greater effect on the frequency response of the recording. More than any gains you could get from upgrading to a hi-res streaming service. You have to have your speakers and your room in order before any of those differences will be appreciable. Additionally, if the reverb time of your room hasn't been controlled in the low frequencies a record with tight, articulate, bass is going to sound dense and muddy as those frequencies echo and build up in your room.
Just something to keep in mind when debating the merits of hi-res vs. a 44.1k mp3.