Tell you what. I'm not going to even get into this anymore. I'm simply going to let the GAO and DOT&E reports do the talking:
GAO’s ongoing work on the F-35—Joint Strike Fighter—program shows that the program has continued to experience development and testing discoveries over the past year, largely due to a structural failure on the F-35B durability test aircraft, an engine failure, and more test point growth due to software challenges than expected. Together, these factors have resulted in delays to the program’s test schedule. In addition, the F-35 engine reliability is not improving as expected and will take additional time and resources to achieve reliability goals. With flight testing of more complex software and advanced capabilities still ahead, additional technical discoveries during testing and subsequent design changes are likely. At the same time, the Department of Defense (DOD) plans to significantly increase production rates over the next 5 years. Increasing production while concurrently developing and testing creates risk and could result in additional cost growth and schedule delays.
Manufacturing progress has continued despite mixed supplier performance. The aircraft contractor delivered 36 aircraft as planned in 2014; however, none of these were delivered with warfighting capabilities. However, the labor hours needed to manufacture an aircraft and the number of major design changes have continued to decline over time. Supplier performance has been mixed, and late deliveries could pose risk to the program's plans to increase production. The contractors are taking steps to address these issues.
Cost and affordability challenges for the F-35 persist. To execute its current procurement plan, the F-35 program will need to request and obtain, on average, $12.4 billion annually in acquisition funds for more than two decades. From fiscal years 2015 to 2019, DOD plans to increase development and procurement funding for the F-35 from around $8 billion to around $12 billion, an investment of more than $54 billion over that 5-year period. This funding reflects the U.S. military services’ plans to significantly increase annual aircraft procurements from 38 in 2015 to 90 in 2019. Annual U.S. procurements peak at 120 aircraft in 2022, and will require between $14 and $15 billion annually for nearly a decade. It is unlikely DOD will be able to sustain such a high level of annual funding and if required funding levels are not reached, the program’s procurement plan may not be affordable.
http://www.gao.gov/products/GAO-15-364
And here is a good writeup on the DOT&E Report below.
http://www.dote.osd.mil/pub/reports/FY2014/pdf/dod/2014f35jsf.pdf