CFL's are great. They are more energy efficient, but they do cost more. Do you realize, though, that CFL's aren't great everywhere? I found this out when we blew two in our bathroom. I e-mailed GE to let them know that they had only been installed in October 2008 and failed to work only months after. Though I pitched the e-mail, I did do some fact finding to help y'all not lose your expensive lightbulbs.
CFL's aren't good in the bathroom because of moisture and constant on and off. CFL's are designed to take a few to fully brighten and the continual on and off, such as the bathroom or a hallway, shortens their lifespan by upwards to 85%. Bummer. The US Energy Star program suggests leaving lights on for 15 minutes to avoid this problem.
I also learned that at the end of their life, CFL's produce 70-80% of their original light output. Hmm. Good to know. I don't recall having read this on the package, though.
So, I wanted to pass energy and money saving tips on to you. Keep those CFL's on for 15 minutes for maximum bulb happiness. For more information about CFL's, go to Wikipedia or to this GE link. There was a very interesting article in Time Magazine on January 12, 2009 about America's Untapped Energy Source: Boosting Efficiency. It's amazing how much energy efficiency can save us!