Jim Morrow’s review published on Letterboxd:
First, the performances are uniformly excellent, but Phoenix and Hoffman are in rarified air territory here. Second, it's not about Scientology, and I believe that was the reason so many people disliked or misunderstood it. Third, like any truly good or great film, it reveals much more with every viewing, so if you have a taste for movies that go beyond basic story telling, and you're willing to return to a film a few times and see it from different perspectives, then this one rewards that in spades.
Both of these characters are damaged, both hiding behind an illusion or wall, and each with a crutch; booze or religion. They are both highly protective of their respective walls, and each one's actions mirror the other's. In the end, have the walls broken down, or are they even higher than before? Are we all looking for a "master" because the fear that we have to find that in ourselves, and that there is no perfection is too overwhelming? Are all the things we build up to comfort ourselves, the beliefs, religions, cults, material pursuits, drugs, etc. just illusions, made of sand? I'm pretty sure that PTA doesn't have the answers either, but if the idea of spelunking through the mind appeals to you, then this is a deep cave.