I agree that one experience does not a bad airline make. However, if you are inconvenienced, you have the right to express your displeasure. As much as I love UA and the Star alliance, they have inconvenienced me in the past several times, and they have heard about it. I simply write a very professional email expressing my displeasure, but at the same time pledging my continued loyalty to UA and Star and also express my faith that my inconvenience will be alleviated by a voucher or something. It has worked wonders in the past.