And yet Mailplane continues to pay the salary of a sole developer. Maybe Sparrow's aspirations were too big for an email client? The interesting thing about Mailplane is that it targets an arguably different user base (gmail power users?) at a higher price point ($24.95). Personally I'm a Mailplane user because I prefer gmail's web-interface and I have three accounts to juggle. I never saw the appeal of Sparrow over OS X's Mail.app. And I'm still waiting for something like Mailplane for the iPad.
Maybe Sparrow's aspirations were too big for an email client?
Why is it people keep painting a $25 million dollar exit and jobs at Google for a year and half's work as some kind of failure? It looks like like a home run to me.
Because it is, in terms of the goal of building an awesome app and a sustainable business solving peoples problems with email. It is a personal win for the founders but not the one I imagine they were hoping for when they set out.