It’s a bit of a read but this article lists the the current problems, and the basic architectural problems in excruciating detail:

The F-35 still has a long way to go before it will be ready for combat. That was the parting message of Michael Gilmore, the now-retired Director of Operational Test and Evaluation, in his last annual report.

The Joint Strike Fighter Program has already consumed more than $100 billion and nearly 25 years. Just to finish the basic development phase will require at least an extra $1 billion and two more years. Even with this massive investment of time and money, Gilmore told Congress, the Pentagon and the public, “the operational suitability of all variants continues to be less than desired by the Services.”

Gilmore detailed a range of remaining and sometimes worsening problems with the program, including hundreds of critical performance deficiencies and maintenance problems. He also raised serious questions about whether the Air Force’s F-35A can succeed in either air-to-air or air-to-ground missions, whether the Marine Corps’ F-35B can conduct even rudimentary close air support, and whether the Navy’s F-35C is suitable to operate from aircraft carriers.

He found, in fact, that “if used in combat, the F-35 aircraft will need support to locate and avoid modern threat ground radars, acquire targets, and engage formations of enemy fighter aircraft due to unresolved performance deficiencies and limited weapons carriage availability.”

The details follow, and while some might eventually be fixed (late and expensive) a lot of these are artifacts of the basic architecture of both the plane.

This is going to be a complete cluster f%$#.