The F-35 is an expensive platform with which to replace the entire inventory of AF, Navy and Marine fighter and attack aircraft.
But
For it’s air superiority mission, it is awesome. It gives the President a tremendous option in considering threats as they arise.
Without identifying the country, let’s say the Organization of American States authorizes the use of force to restore democracy to a particular country in this hemisphere, equipped with Russian military equipment.
With a squadron of F-35s, the President could be pretty confident of controlling the airspace over this unnamed country. In the meanwhile, F/A-18s - more robust in terms of munitions packages and time over target - made sure that tanks and other armored vehicles remained in place.
“For its air superiority mission, it is awesome”
The F-35 isn’t an air superiority fighter. The role you describe is the job of the F-22.