The unstoppable visual power of Mononoke continues strong through the "Umibozu" ("Sea Monk") arc, revolving around the revelations of a prestigious monk's dark past and repressed regrets, played out on an unbelievably ostentatious boat trapped in a "Bermuda Triangle" of monsters and ghosts.
It follows the same formula: everyone acts a bit suspiciously, a terrible monster shows up and is barely fought off, there's lots of talking and hinting about the true nature of the tragedy that formed the monster and the truth is only dramatically revealed when the monster reappears and is poised to strike. There are some hints at something deeper going on, however: the myserious "medicine sellers" seems more interested in banishing ayakashi than in saving anyone (and he seems to enjoy it), and he goes through some mystical release/transformation to fight the monster this time.
But, as I've said before, boiling Mononoke down to its basic formula does it an injustice. It's the style and (especially) the incredible visuals that form the core of the show. Once again it deftly deals with dark, tragic material through suggestion and imaginative symbolism. It may be difficult to follow at times and risks the same sensory overload that drove people away from Gankutsuou: The Count of Monte Christo but that's exactly what makes it so riveting.
An otherwise rudimentary (if refreshingly dark) ghost story is given a whole new dimension and depth with the show's visual style. Highly recommended.