The F-35 is designed as a multi-role airframe. Multi-role frames are generally not going to be the best at any one thing because of trade offs that have to be made. You want an air superiority jet, that's what you design from the ground up (F-14, F-15, F-22). You want ground attack, that's what you design (A-10). You want something that can do a little of both, but neither as well as a single design, you build that (F-16, F/A-18, F-35).
Is it too damn expensive? Yes.
Does it have growing pains? Yes.
Has every new fighter aircraft gone through this? Also yes, but not in the age of keyboard warriors who don't know what they are talking about.
Pretty much. The aircraft at least is flying now (all three iterations), and getting it's test on, so the can iron out the initial bugs in the system. This is, after all, government procurement ;)