The Smithsonian is ebullient about it:
Weighing 10,000 pounds empty, the Thunderbolt was the largest single-engine fighter built by any country during World War II. Fully loaded with pilot, fuel and armaments, it topped out at more than 17,500 pounds—yet was exceptionally fast as a fighter-bomber, achieving a top speed of 426 miles per hour. It was arguably the best ground-attack aircraft America had at that time.
For others like myself, not so much: on 15 April 1943 my uncle, Don Gaston Shofner, was killed in his over Long Island Sound when fuel got on his exhaust manifold and the plane exploded. He wasn’t alone; others were killed in numerous accidents before they even got the chance to engage the enemy. Like much of the U.S.’ war effort, there was a great deal of trial and error, with tragic results. The sacrifice of those who were the USAAF’s “guinea pigs” in making the plane reliable is not one that this country has been quick to acknowledge.