You say you evaluated Cloudant and MongoDB, among others. Why did you decide on Cloudant?

-Recommendation by the Windows Azure team. -Scalability. -After I got my head around CouchDB in a weekend it was so easy I didn't need to look any further.

I used the documentation on the Cloudant site over that weekend so that definitely played a large part too.

High level -- what's it like writing for windows mobile vs iOS/android?

I've only just started developing for Android (Foundbite's next version) so can't really give an opinion. Visual Studio is great to work with though. There are only 4 screen resolutions for Windows Phone so in that sense it's easier to develop the UI.