Scientology works. It is an effective applied religious philosophy, and produces excellent results. Moreover, the many social programs of the Church of Scientology have helped millions of people the world over, in such areas as disaster relief, education, drug education and rehabilitation, criminal rehabilitation and morality.
Um, you might get to wear a cool navy uniform... make it to the top and you can have a good time viciously abusing the people beneath you, if that's what you're into. Cons: Founder is well documented as a pathological liar, very likely both schizophrenic and a psychopath (or in any case shockingly crazy), and overtly cared *only* about money and power for himself.