Ew. iOS is a tough market. Getting downloads is difficult even if your game is free, never mind paid. So I understand ads in games. rainblocks has ads on iOS and Android. Getting those downloads is the goal.
But look at Shinjuku Dungeon. It gives you a standard touch-screen controller except the buttons are ads. Five minutes of play makes it seem like the game is just moving around and solving puzzle via the d-pad. But the idea that "Maybe they'll accidentally push an ad!" is just gross.