***** Potential SPOILERS *****
Tenet follows the great Nolan tradition of really bad sound. It annoyingly loud and at times you can't hear what characters are saying. Nolan, fire your sound mixer. If you're mixing it yourself, fire yourself and get someone who knows what they're doing. Really s#!t work.
It's also really badly edited (whether that's strictly editing or the script itself, who knows?). Some scenes happen with zero segue, and then at other points the movie gets bogged down. Unfortunately it's hard to care about the characters and story. Everything is a bit too rushed, and you don't have time to really soak it up and enjoy it.
The time-bendiness is classic Nolan, but it's obscure and difficult to get a grasp on. Maybe the film will fare better with repeated viewings, but after a one-off watching it's potential tantalizingness is significantly diminished. Yes, there are some great things to ponder, but the core narrative of the story is buried so deep that it becomes a little ineffective. There is a reason for the time-bendiness, but it's obscured and to be honest I was a bit weary by the time it was all revealed.
The basic plot of the film is okay, but I didn't really dig the "inversion" part. It's clunky and odd. Some great ideas and scenes, but overall it was difficult to follow clearly.
Plus, the time-bendiness is never really explored in a way that lets you revel in it. Rather, it's hidden and revealed bit by bit which unfortunately means that you don't get to fully enjoy it.
There's no theme here, at least in the way that other Nolan films have; Inception was about redemption, Interstellar was about the power of love or something, the Prestige was about revenge etc etc. This one doesn't really have that. Not a bad thing, though.
The acting is okay, but Nolan never gives the audience time to settle in. The relationship between Washington and Debicki's characters seems to be important, but why? Who knows? Neither character is given time to answer that question sufficiently.
This is really the main problem here. The pacing of the film is a bit all over the place, and it's hard to get involved with it. It jumps about from scene to scene at times with no explanation. I mean, I was able to follow it, but a few times I was asking "What are they doing and why?" and it took a while to understand (I'm not talking about the time-bendiness here either), which really diminished the film. In one scene, they're trying to get to a particular character. Why? You don't know till the scene is halfway finished. So instead you just sit there and watch them do some admittedly neat action scenes, but it's undermined because I have no idea what the goal is.
Overall, it's okay. It spends too much time trying to hide it's big reveals for them to be effective, and it's too rushed/badly paced to get into. I hope that repeated viewings (on Netflix) will make it better.