Hi — No offense, but personally I find ads quite annoying when they interrupt game play so end up harming the game experience. I would rather pay for access to higher levels. Someone was talking yesterday about maybe putting a forum discussion together focused on sharing best practice regarding income generation.
I also like the idea of having an in app purchase to unlock a game. Unfortunately in several countries, including South Africa where I am from, we are not allowed to sell on Google play. Ads are our only way to monetize at this stage. I do feel you can make money with ads, if you do it properly and not intrude on game play.