Brix sums up 2012's aim thusly:
Our big goal this year was to establish a new, scalable platform on the phone and in the cloud upon which we can better achieve our mission: to provide a confident, convenient and customized app experience for our customers across the world, and enable developers to rapidly innovate and realize opportunity.
The early numbers being genereated by Windows Phone 8 handsets seem to bear that out, but I'm not sure that the public are ready to credit Microsoft with a complete success in these areas.
Moving forward into 2013, Microsoft are hoping to build up confidence, convenience, and customisation for their customers, while developers can look forward to Innovation through the common design language of the Windows product range, global distribution, and various monetization options.
Brix's full post can be found on Microsoft Windows Phone Developer's Blog.