Score: 8/10. Inception was fantastic and Interstellar was fantastic as well, in terms of cinematography, but also in terms of being fantastic films... Tenet however isn't a fantastic film, it's just a good one.
For the vast majority of the film, the viewer is left confused and confuzzled. The start is confusing, the end is confusing, and most of everything in-between is confusing too... It's just a very confusing film. With that being said, it's a very visually impressive film (like almost all of Nolan's films). The sequences that feature the 'Tenet mechanic' are very impressive and without it the film would barely be a 7/10 film.
Throughout the film, there are supposed 'curve balls' or 'plot twists' that are thrown at the viewer, but I managed to predict at least 4 of them, which really blunted any of the 'surprise' that the film makers intended on inflicting upon the viewer. This doesn't really come down to the viewer being 'smart', it just comes down to the film makers not being smart enough.
Overall it's a good action film: Lots of fighting and lots of explosions. It's not anywhere close as being as good as Inception or Interstellar, but it's still pretty good. 8/10, and would even warrant a 2nd viewing since you probably would be less-confused on the 2nd viewing and thus things would make more sense.