I think I am more impressed with this movie, than I actually enjoyed watching it, for significant amounts of the running time. The direction, the shots of the frigid water, and consuming fog, the sound of that lighthouse, the setting in all it's bleakness, the rawness of nature's most desolate spots, was masterful. Both performances are actors at the top of their craft, even if Patterson's slips in the last act, which is probably more of a script overreach. The whole thing gets a little shaky in the third act, and comes close to the "parody", that Patterson describes Dafoe as, in a bizarre moment. The themes are deep, and obvious, strewn all over the movie, like the seaweed across the rocks, and I won't even get into it, but prefer to take the more topical approach to the movie.
The moments that inspired the most dread, awe, disgust, horror, or apprehension were the final scenes with the "dog", the moments when the characters became merged with the sea in a twisted outbreak of barnacles and tentacles, that was just perfectly grotesque. The last moment of staring at the light. Some of the plot is a little muddled, and wears thin, in the final act, and I didn't care much about either, or the motivations, it worked best to me as spectacle of madness and style. Eggers has a brilliant eye for imagery, and setting, and moments of sheer, blood curdling horror, if sometimes the material went over the top, or didn't land correctly.
For those who loved this, it reminded me of a movie (and countless others are probably part of the inspiration) called The Light at the Edge of the World, from 1971, about two lightkeepers and a massacre by pirates.