One of the first things I do when I am consulting with a client is take down the mission statement! Mission statements, just writing those words are painful. Have you ever seen a mission statement that wasn't full of fluff? "We strive to have superior customer service". Would you strive to have the worst customer service? Customers are smarter than you think they are. And if you are not exceding there expectations the plaque on the wall is not going to save your brand.
Your mission statement is not words on a piece of paper its your brands culture...its how you do business everyday from in-side the walls of your brand. So keep your mission statments short and sweet and keep them internal and concentrate on building your brand and your people.... and your superior customer service will show all on it's own.