Christopher Nolan tells a captivating story with time inversion, what the Algorithm truly is, and explain who all the characters are (the main character is known only as the Protagonist, after all).
That's not to say there aren't quite a few redeemable qualities of Tenet, but what's bogged down this otherwise inventive tale is a collection of missteps - or parts of the film that had to be trimmed down in order to keep the story on track. For instance, practically every piece of dialogue in Tenet is exposition; everything is meant to explain what the Protagonist's mission is, or how each person fits into that plan. Next is the importance placed on Kat's role; she's first introduced as someone who can act as a bridge between the Protagonist and the villain, Sator, but she's later developed into a primary player. After that, and perhaps most egregious, is that the story's main tool (time inversion) and the MacGuffin (the Algorithm) are left mostly unexplained, and audiences are even told to not worry about trying to figure them out.
Nolan clearly an idea he wanted to tell in an exciting way, but in hindsight, his movie is actually let down by being a movie. By the time audiences can catch up and understand at least the basics of what's happening, the Protagonist has already met, and moved on from dealing with, Priya Singh. From there, more factors are introduced into the equation, resulting in a puzzle that's practically designed to be unsolvable. Sure, parts of the film are overtly explained, but so much is pared down and glossed over in order to, again, stay on track. If Nolan had turned Tenet into a miniseries - 6, 8, or 10 episodes - it could've been truly outstanding, and it would've given him time to work through the kinks.
Tenet is by all means an ambitious film and it contains gripping action scenes from start to finish, but the spectacle can only carry viewers for so long. Much of Tenet becomes overwrought the more information is revealed, and that ultimately boils down to a concern of plot density. A miniseries would've allowed Nolan to map out the biggest beats and reveals over the course of several hours, permitting him time to properly guide viewers through the story, because by the time the temporal pincer movement takes place in the final act, people still have so much catching up to do that they may feel emotionally empty watching the battle. As a result, the biggest part of the film comes off as anti-climactic.
In many ways, Tenet could've followed in the footsteps of HBO's The Stand, which could be done as one or two movies, but the story would suffer from being incomplete. But again, Nolan's vision for the big screen is tough to beat, and what he delivered with Tenet is imaginative. The only thing is, too many ideas are thrown at audiences for them to matter; it, again, can leave people feeling nothing once it's over.
