How does one even start a review of a Transformers movie anymore? Five films into this franchise, the movies continue to churn out nearly identical special-effects fodder, and either that's what you're going to the theater for, or you know to stay away. Needless to say, Transformers: The Last Knight isn't going to make any new fans in this franchise. The movie is incomprehensible gibberish, whether you're a fan of these movies or not. So it's simply a question of "Do you care?"
Attempting to explain the plot of Transformers: The Last Knight is an exercise in futility. If you've seen any previous Transformers film, then you'll have the gist down. There's an object of immense power which has been hidden on Earth for centuries. The bad guys want the object in order to do bad things, the good guys go after it in order to prevent the bad things. Explaining the story in any more detail might make your eyeballs bleed. It involves King Arthur, Merlin, a Da Vinci Code-like centuries-old secret society, a chosen one (two of them actually), and a couple of character introductions with names that classic Transformers fans will recognize. They won't actually be those characters. They'll just have the names.
Once again, Mark Wahlberg takes center stage as Cade Yeager. He's gone into hiding with what remained of the Autobots at the end of the last film, occasionally popping up to play vigilante hero and save other Autobots from the military organization that is hunting them down. Not to be confused with the one that was hunting them down in the last movie. This one's different. Joining Yeager are a 14-year-old girl he rescues named Izabella (Isabela Moner) and an English history professor named Vivian Wembley (Laura Haddock), who's important for... reasons.
One of the major criticisms lobbed at the Transformers movies, even by those who might otherwise enjoy them, is that while the films have Transformers in the title, they are really much more about the human characters. This may be more true in Transformers: The Last Knight than in any previous entry in the series. A significant number of named Transformers show up for the beginning of the film and then disappear nearly entirely until the climax requires their return. Only Bumblebee has a significant presence throughout the movie, and even he is left to play the third wheel to Wahlberg and Haddock. He's mostly ignored, even when he's on screen.
Of course, the same is true for some of the human characters as well. Isabella Moner opens Transformers: The Last Knight with a fantastic action sequence which shows the 14-year-old Izabella to be smart, capable, and driven before she's relegated to "kid sidekick," making all the childish decisions you'd expect from the trope, for the rest of the movie. That's when the story bothers to do anything with her at all, as she's also removed early on so that Wahlberg and Haddock can focus on their shoehorned and utterly unnecessary burgeoning relationship.
Oh, and Anthony Hopkins is in the movie, too. He provides all of the film's expository dialogue. And boy is there a lot. For a film that's so paper thin, the mythology has become awfully dense. Because none of the previous four films have set up any of what takes place in Transformers: The Last Knight, the movie has a lot to explain in order to keep you up to speed. Also, since the movie was already two and a half hours long, the film has to stop and have a character tell you what they were doing while off screen. Because the information was important to the plot, but not important enough to actually show.
As a visual spectacle, Transformers: The Last Knight certainly delivers. It's got the sexy sports cars driving fast and the massive robots blowing things up. While I honestly felt like each individual action sequence wasn't as involved as previous movies (maybe that's just desensitization), the finale makes up for it with a massive battle encompassing all the humans, as well as the previously MIA Transformers. The action is certainly big, but it's far from satisfying. We don't see anything here that we haven't seen before in the previous installments. At least the last movie added dinosaur robots. This one does add something new to the mix, but we get so little of it, it's hardly worth bothering.
In the end, Transformers: The Last Knight is exactly the movie that you think it is. If you think it's a fun time to watch big screen magic and eat popcorn, it is that. If you think it's a cinematic mess without much point, you are also correct.