Shea Gallagher’s review published on Letterboxd:
Almost completely incomprehensible; things just happen with absolutely no explanation or decipherable reason (people complaining about Nolan falling back on exposition again in this...did we watch the same film? The exposition here is so sparse and half-arsed that they might as well not have bothered), we are immediately dropped into the deep end and it doesn't get any easier after that, and there's something to be said for the fact that the 90+ minute discussion with my friend afterwards was focused just as much on trying to determine basic plot points as it was to make sense of where things end up.
So much of this is just a barrage of images and sound, in many ways the extreme form of what Nolan has been working towards over his last few films. Once again, he's folding time over on itself, covering the same geographical spaces at different temporalities, except this time it's baked into the story of the film. But whereas normally he gives us a solid foundation on how time and place relate to each other, here your brain is doing all the work (or gently switching off) as you try and make sense of some truly baffling imagery. The important thing is, amongst a chaotic structure and an even more chaotic sense of stakes, cause and effect, I think Nolan somehow pulls it off.
This is the first time I've felt Nolan is actively trying (and succeeding) to make things hard to understand. It's even there in the dialogue at one point: "Don't try to understand it, just feel it" - which is hilarious coming from somebody often criticised for his cold, emotionally stagnant approach and penchant for trying to pseudo-intellectualise basic ideas. While I'd offer Inception up as a counter to that, Tenet is certainly a film lacking in accessible humanity. But essentially there is nothing accessible about this, a deliberately obtuse and confounding experience, and one I enjoyed very much. At this stage I really do think this is Nolan's most interesting film, in that even if it is thematically empty (which it isn't) then it's at least damn fun to think about.
I have a lot of thoughts and questions about this, and I will write better things about this at some stage, but this definitely needs more time and more watches. For those of you in the USA, please don't go out and see it! :)