On Windows Phone, every app has the ability to offer a free "trial" version. So you can make a paid app, but still let the user try it (with less features, or ads). I think this mechanism is ideal.
Windows Phone is not exactly a sterling example of developer success, is it?
What do you mean?
Windows Phone has the best mobile programming environment there is. The tools are much better than anything you can find for iOS and Android. I know, I programmed apps on all major platforms.
So is it a developer success? I would think so. Is it a consumer success? Not really. But it's consistently gaining marketshare, and is becoming quite popular in Europe.
And no, I don't work for Microsoft.