The F-35 models are all very impressive aircraft. If you had the opportunity to see one up close, I think you would agree. I actually was involved in the design of various parts of the F-35B propulsion system, and it is a significant leap over any other STOVL aircraft. All the public criticisms you read regarding the F-35's capabilities should be taken with a grain of salt. While the program costs have gotten out of hand, that is mostly due to lack of discipline by the program management. You cannot blame the primes like LM, P&W, R-R, etc. for agreeing to being paid for modifications proposed by the customer.