Graham Austin’s review published on Letterboxd:
What The American Friend lacks in compelling plot, it makes up for in pure mood. It plays almost like a Coen-esque black comedy version of noir tropes, upping the ineptness of our in-over-his-head protagonist to ludicrous proportions. It's not enough that he's (maybe) dying of some unspecified blood illness, or that he's thoroughly unqualified for the job of killing people for money, but he's also a total klutz. There's a surprising amount of humor here, such to the point I wouldn't even be surprised if the importance of being a picture framer was all done for the sake of a visual gag where he hangs a frame around his neck (he's been framed!). Characters sort of just come and go in this black comedy of errors, and I was left unclear what the ultimate motivation behind some of them, like Hopper's Tom Ripley, were beyond the surface level. I was under the impression that most of Hoppers scene were coked-out improvisation rather than anything scripted, and yet they still contribute to a uneasy mood and were captivating in their own maddening way. The film is at its best when exploring the twisted, almost romantic, camaraderie that develops between Jonathan and Ripley as they embark on their clumsy murder plots together. The cinematography is as careful and beautiful as the narrative is messy and ugly, making for a powerful mixture of its discordant elements. I wasn't ultimately sure what I was supposed to take away from the film by the end, it seemed paradoxically both overly-simple and strangely complicated in both plot and theme, but boy did I enjoy basking in the ambiance.