"Going Clear: Scientology and the Prison of Belief"
Likely what you know of Scientology is, at best, incomplete. Sure, you know about Xenu and the entire prehistory from Scientology which is briefly covered in this documentary, but what you probably don't know about is exploitative nature of the church.
Most of the doc consists of interviews with people who have left the church (when the makers are done with that interviewee they show a graphic saying "X left the church in <year Y>") so it is undoubtedly biased. There is some archive footage of followers like Tom Cruise and John Travolta, but my guess is that the makers did not bother to try (at least too hard) to get Q&A interviews with them or the current leader, David Miscavage, given the litigious nature of the church.
While the basic tenants of Scientology pooh-poohs psychology in general, what much of Scientology deals with is people attempting to go "clear". In order to do this, that person must reveal their own inner demons to a church official who watches a church's "e-meter" to see that during this revelation (and its repeats) that the revealer's reactions to these memories gradually diminishes while at the same time the official takes notes which are filed away in the church's library. In some cases--especially for celebrities--these attempts to go clear are also recorded. Now, regardless of one may think of the act of Catholic confession, one thing that is assumed that the Roman Catholic Church would never use a confession against the confessor. This library is part of why Scientology maintains a tight control over its members.
(To be sure: the church's beliefs include a form of reincarnation so that one must become clear for one's memories in one's past lives. While these may be a limited use in term of keeping control of members, they are useful monetarily because no matter how far back one might go there are always further past lives to "clear").
There is a lot more information like how Tom Cruise enjoys the exploitation that Scientology grants him. He expressed the idea that he wanted to married in a garden to Nicole Kidman, so in the desert compound that the church maintains Miscavage ordered that a garden be created (and torn down to be rebuilt again because Miscavage didn't like the first garden). It may be that Cruise is deluded in believing that these church members are donating their time for the benefit of the church, but he must know that he does get a lot of things for free (or at least for the above cost of becoming clear).
Recommended, especially if one wants an understanding of the Church of Scientology.