Not very hot. It's pricey, but not too hot. Top speed is a sluggish Mach 1.2. The poor old F-102 of 50 years ago was that fast. Max altitude is 40,000 feet, again, not much. the U-2s of the 1950's could do 70,000 feet. Peak maneuver load is limited to 5.6 G. The long obsolete F-106 could pull 8 G back in the 1960's. Figures come from Aviation Week. Oh yeah, and the internal gun won't work until the next software upgrade, sometime in the future. And it can only handle two air to air missiles. The old F-106 carried five.
The F-35 people claim these restrictions will go away after the next software upgrade. They are currently flying software block 2B. Block 3F, promised sometime in the future, will at least make the gun work. The G limitation is caused by weakness in the engines. Pull more than 5.6 G and the engine flexes under the G load enough to let the compressor blades rub on the engine casing, with disastrous results, like engine fires.
And, to add insult to injury, the Russians have developed a new radar said to pick up F-35's despite the stealth design of the aircraft.
From the sounds of it, we might do better going back to the old Viet Nam war F-4 Phantom.