Our first release, Fotomoji, was fun but a total commercial disaster! It was our first purely ad-driven app, so there was a lot of learning about the ad networks, and the need to "optimize" the number and size of ads shown. Yuck. I think the IAP route much cleaner for a Free app if one can engineer the app to support IAP in a natural way. In terms of being ad based we made a strategic error in that we could only put an ad against the fotomoji creation, not the viewing. And the viewing was 10x the creating (at least), so yeah errors were made. It would have been better to cut a deal directly and bake a coke can or something into each image, so when it was shared everyone would have seen the ad impression. The deepest error though was even though our choice of emoji effect was timed just right for the late 2015-2016 emoji infatuation wave, and the effect of a mosaic made out of emojis sounded good, and was engineered amazingly well, at smartphone sizes and social media resolutions the output was too often "weird" rather then "awesome". And really that's all there is to it. If the effect had been awesome, all the other issues could have been addressed. Now the algorithm would be amazing for a billboard or print ad, so if any marketing company is reading this, let's talk. :-)