I'm writing a fairly complex iOS app, and I opted in for storyboards in it. It doesn't handle 100% of navigation, because I only was invited to work on the app at some point and I didn't feel to rewrite the whole thing, but I use it for a substantial part of UI. It gets a while to get used to, but then you have this very cool overview of this whole part of the app. Some static parts are done 100% in IB (like a menu with grouped-style UITableView, utilizing static cells), others only use placeholders which are filled in code. But it works, and it works pretty well.