Is using Ad Networks worth it?

[CockyCulture]

Hi,

I've found myself in an odd position, currently my game Pocket Ninjas is in the top 25 free games and top 50 free apps. It was totally unexpected (I have done zero advertising and it hasn't been featured) and has been downloaded roughly 500k in the last week. I have some IAPs that are making me some very solid revenue but have been inundated with emails from various Ad Networks that want to help me further "monetize" my game.

I guess my question is since I have ZERO experience with Ad Networks, does anybody have any insight they could offer? Personally I hate when I download a game and am faced with ads and never expected or thought about including any in my games, but I also never expected a game I made to be much of a hit so I don't want to automatically dismiss anything either. Any thoughts would be greatly appreciated.

Thanks,

Tony