Lots of stuff here:
http://media.bloomberg.com/bb/avfile/rboZtDuN4Gwk
The 20-second version:
A lot of remaining aero-mechanical problems on the B. No sign that they can't be fixed, but fixing to target lifetimes within the weight budget will not be easy. For example, clutch materials that avoid overheat while providing design lifetime are still in the research stage.
Still dealing with coatings on the H-tails getting heat damage at Max A/B.
Thermal management/aux power system still being pain in the a**.
Mach 0.8-1.2 accel time and sustained g specs relaxed. F-35C accel time increased by 43 seconds - I repeat BY not TO 43 seconds. (Total time is >110 sec by my calcs.)
Software continues to run late and fell further behind schedule in 2012.