Although Taptitude is multi platform, the team don't think they have enough data (yet) to really analyse the impact on other smartphones.
I love the correlation on downloads tracks the general health of the whole Windows Phone ecosystem - when it went quiet in the summer of 2012, so did the downloads of Taptitude. And they now have had a consistent performance for 2013.
There's also discussions about how they handle the app crashing (statistics are available from Microsoft to developers), the performance of the in-app advertising, and their monthly earnings (averaging around $15,000 per month during 2013).
The model is still working for them, and they believe that there's more room in the Windows Phone platform, and as a company they want to transfer the model that works for WP into iOS and Android.