I wrote a GPS app (for offroad use) in December last year. It's a pretty poor app, and because it was crap I priced it high to discourage buyers. And now I'm getting mailed by Microsoft because they want to give me my money. It was quite amazing - I never tracked the app's performance, and ignored it, because I only wrote it to get familiar with the tools.

I've not written for any other platform, so have no comparison to offer.