I have nothing against personality testing. I have taken many over the years that were accurate in their assessment and helped me learn more about myself and more about others.
I hate the way that companies - particularly hiring managers - use them. I've seen them abused in terms of making hire/no hire decisions and in limiting someone's career. I knew of one company that if the test said the person was not a good manager candidate right now, decided that person would never be a good manager candidate.
I've discouraged the use in every company I work for (and am leary of working anywhere that uses them). Not because of the validity of the test or the organizational psychologist's reputation, but because people who are not experts do not know how to use them.
Best way to use them - give the results to people and let them devise ways to grow from the information.