Existing Android App not that bad
I use the existing Android app and to be honest once you learn the slightly weird navigation it's actually pretty good. It's not the quickest to load so I also have a 3rd party widget that allows you to control the Sonos quickly through your home screen (though I'm pretty sure the app has had it's own widget for a while).
I haven't spent too much time playing with the new app but it has a pretty clean look and and the navigation does seem to be improved.
Since Amazon and 7digital streaming are both already supported I suspect that Google Music will be along within the next year.
While an updated Android app is all well and good it was much lower down on my wishlist than a Linux client and proper BBC iPlayer support. Live radio is great through TuneIn but the catchup library available for the BBC leaves a lot to be desired, more often than not I just plug my phone into a Sonos load the iPlayer app and re-direct the Line in to whichever rooms I want to listen in.