Well done post, and definitely some interesting data to look at here.<p>The one point where I think you may have undersold Google is the interoperability of their Music service. They sell their music without DRM (similar to Apple) so it can be played anywhere. Also similar to Apple they have a player built in HTML5 so it can be accessed on most devices without even needing to download the song and play with a native player. This should be reflected and I believe should swing the interoperability category heavily in Google's favor since books and music are both accessible everywhere.