Microsoft's biggest weakness is that they still don't realize how much they suck. They still think they can write software in house. Maybe they can, by the standards of the desktop world. But that world ended a few years ago.
Paul Graham's on Microsoft is as relevant today as it was when it was written in 2007. Judging by their efforts with Windows 8, they still suck, 2013 is going to be a tough year for them.