It's an article about the need for paying attention to what is going on with your customers and competitors, especially in the middle of a startup. In the past, I have made all of these errors at the same time, which may explain why I am a thousandaire not a millionaire.
Every startup should be built around the notion of customer development anyways. I'm glad to see the customer development and lean startup movement gaining traction.
I'm glad too. @ericries is doing a phenomenal job pushing that movement.