When I first watched Tenet, I didn't think it was that great.  But upon a second viewing I have changed my mind, this movie is in fact really good.  It's definitely one of the most confusing Nolan films, which can detract from the overall feel of the story somewhat, although it certainly creates some great conversations with friends after the movie is over.  It's amazing how much clearer the story becomes on a second viewing.  The characters and acting are all good, and fit the vibe of the movie perfectly.  The visuals are really good, especially the VFX, and the soundtrack is of course phenomenal, as it is in every Nolan film.  The action is good, but sometimes a bit weird and hard to follow (if you've seen it you know what I mean) but luckily it's still entertaining.  A great movie, and a perfect movie to watch if you want your mind fucked.