I heard a report about this on NPR about 30 minutes ago. The report stated that the F-35 program is 7 years behind, and 70% over budget. The report also said that some in the government are saying that the F-35 program has now become to big to fail... Go figure
I also remember reading other articles that stated that pilots don't like to fly the F-35's. One of the reasons cited was it's single engine design.