For a one-person shop, getting a game out at all is pretty amazing! I certainly see the appeal of Game Center. I'm not knocking it, we just wanted more flexibility and control. We started with a single API server and single DB server, but it was still over $200/m, so it was a cost we were willing to eat personally and experiment with - but we knew it had to become self-sustaining quickly, or we'd have to rethink our strategy.

As for ads - iAd pays about 75% as well as RevMob and Chartboost - believe it or not. That said, this month we're about 28% banner, the rest interstitials - they're worth it, as long as you don't abuse them.