Dumping Symbian made a lot of sense. Replacing it with MeeGo seemed like a decent idea, but it was never clear if MeeGo was really ready to replace it (thought early reviews of the N9 made it look promising at least), and Nokia wasn't ready to dump Symbian. Ditching both for something else was a hard call, but probably wasn't the wrong one.

But, why announce when he did. The chosen OS wasn't out at the time, and Nokia had just gotten ready to ship their shiny new MeeGo flagship as well as a handful of new Symbian handsets. That announcement basically made all these new devices worthless. He could have at least kept the announcement silent for 6 months and see if the phones gained any traction. You can argue that they wouldn't have, but at least their sales numbers would have looked better. His timing was terrible; HP terrible.

And why WP? The OS wasn't finished and was missing some pretty basic features when it finally was launched. As countless people have said already, Android would have made a lot more sense here. They could have customized it and potentially even brought Symbian apps over and it had the added advantage of already having a solid foothold in the market.