Microsoft's Windows Phone seems to be doing well with 75,000 apps and games being certified by Microsoft this year. Microsoft also approved over 300,000 app updates this year, which shows that developers aren't giving up on the apps they release for the platform, something that can either make or break an ecosystem.
Microsoft has been doing their best to entice developers to come to the Windows Phone platform, because without them, Microsoft will have a tougher time selling devices. Carrier billing has been a big part of the Microsoft Store's success as well, as it has led to over 2x paid downloads vs credit card billing.
Convenience is key, as the carrier billing shows. Microsoft devices saw an average of 54 apps downloaded per phone and revenue has jumped 40 percent in the 30 days since Windows Phone 8 SDK was released.