Anlock say that both the iOS and Windows Phone version of the app has received promotional placing in the respective app stores and both have received good reviews (4-5 stars). However, the Windows Phone version has outsold the iOS version by 5 to 1.
Anlock's First Words: Learning with Animals
As the developers themselves point out the difference is mainly about the level of competition. There are fewer apps in the Windows Phone Marketplace, so it is easier to get noticed.
So how can a well written iPhone app, with great reviews, featured by Apple and supported with marketing efforts, perform so much worse than the exact same, equally top rated, app on WP7? How is this possible, given Apple’s market share in smartphones (and compared to Microsoft’s)?
The answer is quite simple: Apple has 500.000+ apps on the App Store compared to only 30.000+ on the Windows Phone Marketplace. The potential, in terms of devices in the market, of the App Store is huge compared to that of the Marketplace but, at the same time, there is fierce competition and a LOT of noise in the App Store, making it extremely difficult to stand out.
What is interesting, at least in the case of Anlock, is that the less crowded nature of the Windows Phone Marketplace has outweighed the disadvantage of a much small installed user base (i.e. number of devices sold).
The situation is clearly going to be different for every developer, and it possible to find data to make this kind of assertion about almost any platform. However, posts of this kind are valauble endorsement for Microsoft and do suggest that the Windows Phone Marketplace is maturing and adds weight to the idea that a multiple platform approach to mobile is the wisest course of action for most developers.