I started as a Windows developer when I was 12, and enjoyed the transition from ugly MFC/VB6 to .NET, which was pretty well-designed.

They lost me when they changed “the” data framework from ADO .NET to LINQ to SQL to Entity Framework, simultaneously obsoleting Windows Forms in favor of WPF, and later in favor of Metro-ish Silverlight.

All this while Apple sticked with Foundation and Cocoa and built greater / high-level frameworks around them.

As Dare put it in the comments: “... platforms are being born and dying so often that it seems you need to subscribe to Mary Jo Foley's latest breakdown of Microsoft internal politics before deciding what to bet on...”.