Some of the worst critics of the church still hold that Mr. Hubbard's teachings are worthwhile -- a separation of the method from the current church leadership.
Ive known a few scientologists over the years. One of them actually ran the local church here, before selling up his successful business and travelling to the USA to work for the church. Apparently he was barely paid enough to cover his smoking habit, but I digress.
The truth of it, in my limited experience anyway, is that the teachings (via the technical sounding terminology, and a set of rules and procedures) gives people who feel that theyve lost control of their lives a mechanism by which they at least *feel* like theyre regaining control. In my opinion it is nothing more than a placebo, but Im sure there may be those who experience a long term increase in their happiness through application of the "tech" simply because it compels pretty fundamental change in your life, which isnt always a bad thing. Sometimes, any plan is better than no plan.
I dont think scientology offers a path to greater success or happiness in life, and it certainly doesnt even remotely live up to the wild claims that it makes. Several elements of it are very obviously (and provably) nonsense, for example, the e-meter and its application.
The unfortunate side of it is that it *is* very cult-like. The techniques they use to get you in and keep you there are very obviously those of a cult. Therefore, there are probably many people who are not happier, and have not gained a placebo feeling of control, but who are compelled to continue. Despite all the pleadings to the contrary, it is obviously very difficult to leave the church for many people.
One guy I know in particular, *still* gets emotion-laden calls from the church many years after breaking off all contact, to the point where he occasionally still spends good money on books and videos that lay unread and unwatched, simply because he does not know how to say no. (on a side note, when his wife told the callers that if they rang again she would call the police, they stopped calling the house and somehow managed to obtain his new and unlisted mobile phone number - freaky).
Can I claim that all of dianetics has no value? Of course not. But the church has tried hard for decades to strangle any amount of usefulness from it. If it werent for all the nonsense that goes with it, I myself might have read dianetics and perhaps even gained some sort of value from it. Given the baggage it now carries though, I wouldnt touch it with a barge pole.
You can then understand why his wife turned into an "SP" 
