Check this post The 7 deadly sins and 10 lessons of a failed startup from Don Dodge on The Next Big Thing:
"Building a startup is the most difficult, and most rewarding, thing anyone can do. Sometimes you can even make some money at the end of it all. There are so many things that can go wrong it is a miracle when a startup actually makes it. It is important to celebrate our successes, learn from our failures, and value them equally. Failure is important...because success is a terrible teacher."