Before continuing, it's worth keeping in mind that the Free Will Defense is only an answer to the logical problem of moral evil (see my previous post for a refresher on the various distinctions). This is not to say that the argument is weak - it just has a particular focus. Further, the logical problem of moral evil was for years so often used by philosophers to dismiss the traditional view of God.
The Free Will Defense made a pretty big splash in the philosophical world. Today, arguing against the existence of God based on the logical problem of moral evil has fallen quite out of style. Contemporary discussions about the problem of evil now focus on the evidential problem and the problem of natural evil. It is really only laymen that continue to peddle the logical problem.
