Despite criticisms, many legitimate, the F-35 has been proving itself dominant in air combat exercises. It was never designed to be an air superiority fighter, but it can be dominant over virtually any 4th gen aircraft. But the real value has yet to be demonstrated, and that is in the networking that is touched on in this article. The author speaks of 4th gen fighters, but the real goal is unmanned aircraft/drones, and integration with battle management networks.
I am led to believe that F-22 pilots really, really like having F-35s as part of the strike package.