Andrew, the common thread is that they have moved from a situation where Twitter wasn't even able to track and monetize their own users, to a world they can increasingly track beyond Twitter into other apps/services' users. They flipped the script, and this phone thing is one hell of a land grab.
Learned a number of things from porting an app from Windows Phone to Android. App stability is a lot harder to manage in Android than Windows Phone due to how activity versus page life cycle works which explains why I've seen more hangs/crashes on my Moto X versus my Lumia 820.
Facebook integration is a lot better on Android as is the push notification story from an end user and developer perspective.
Permissions in Android also are another minefield since even the most innocent sounding features like using a contact picker, saving to SD card or push notifications are communicated to users in fairly scary terms.
Also found at least one down side of using Xamarin is you don't seem to get crash reports in Google Play or Flurry which is a huge downside. Looking for a workaround.
All of these learnings were informed by usage so thanks to everyone who kicked tires on both versions of the app