The latest issue of Consumer Reports contains an update on their long-term testing of LED light bulbs, and the results are excellent. CR found that LED light bulbs (even those with a relatively expensive initial purchase price) pay for themselves several times over, and most bulbs maintain optimal performance after years of use.
Overall, testing demonstrated that an average LED bulb will pay for itself within 3-4 years under normal household conditions. Some bulbs saved enough energy that they paid for themselves in just 2 years.
Durability was shown to be pretty impressive as well. Most of the LED bulbs tested maintained their full brightness after thousands of hours of use, and continued to cast the same color and quality of light. The article even references a pair of bulbs in the Consumer Reports lab that have been on nonstop for 19,000 hours (equivalent to about 17 years of normal use) and still glow just as bright as when they were new.
Learn more or read the entire article on the Consumer Reports website: http://www.consumerreports.org/