I reckon this show will mostly receive meme and troll reviews but I'll try to do this seriously. I've seen a lot of anime over the years, but nothing quite like Dimension High School. This is so far the only show I've ever seen which is basically 50% (CGI) anime and 50% live action. While I have seen live action segments occasionally in anime before, it's never been to the extent which it is here, and never done as a major plot point by itself.
Most likely DHS was intended to be some sort of meta take on the ever so popular isekai genre. Instead of having an anime character being transported from the "real" world to a fantasy one, we here have a group of high schoolers in our three-dimensional world being transported into the second dimension every so often. However, in terms of story it is nothing like your typical isekai anime.
Basically we have a group of students in a Japanese high school and their teacher who every so often get visited by a floating, talking rock with the ability to send them into the second dimension where they get trapped inside a classroom and forced to solve puzzles by giant sphinxes. I've no idea how someone managed to come up with such an absurd premise but I digress. The sphinxes' games are upheld by their absolute rule, which says that if the main characters are unable to solve a puzzle before the allotted time runs out, the sphinx will eat one of their souls in order to collect three-dimensional energy as the sphinxes seek to one day be able to enter the third dimension themselves. If the remaining players manage to solve a puzzle however then they will be sent back to their world, and anyone who had been devoured will be handed back, however in the process they will also lose the one thing they treasure the most in life.
It's a bit convoluted but you get used to the rules relatively quickly. In any case the puzzles themselves are definitely the primary content of the anime and its main selling point. Now there was actually another anime that aired two years ago called Nana Maru San Batsu which was also about quizzes, and I learned there that they can offer a quite unique way for the viewer to interact with the show as you can effectively participate yourself by trying to figure out the answer to the questions before anyone in the show does. However, with DHS there is a bit of a problem if you try to do the same thing. In Nana Maru San Batsu the questions were mostly about trivia which anyone has a chance at knowing, but in DHS they are much more complicated puzzles which are not only difficult and far-fetched by themselves, but they are also pretty much impossible to solve if you are not fluent in Japanese. The intricate word plays and kanji usage which are essential to solving these puzzles are thus impossible for a western viewer to figure out if they don't possess advanced knowledge of the language themselves. I think it's a bit unfair to actually criticize the show for this fact though, after all it's aimed at a Japanese audience from the start and it's not the writers' fault that most westerners lack the necessary knowledge to fully engage in the show.
Nevertheless, even if you can't figure out the puzzles on your own or properly understand the characters' thought processes as they try to do it themselves, I still think they were decently entertaining to watch. And while the anime is certainly very dumb and silly by design, it actually managed to deliver a surprisingly satisfying and well thought-out ending.
Dimension High School feels largely like an experiment. I don't think we'll see a whole lot of anime/live action hybrids in the future as I don't really see the point of it for the most part, but it was an interesting idea at least and you can't say that it wasn't innovative, as weird as it may have been. It is still a very simplistic anime in the end but it doesn't really need to be any more than that. I was struggling trying to think of what I even wanted to rate the show as a whole though, but I do think it deserves a bit more than what MAL is currently giving it at least. The mere fact that half of it is live action doesn't automatically mean everyone has to mass downvote it you know.
PS: Just for the record, this is a full-length show. The fact that MAL has it labeled as only 10 minutes per episode is quite ridiculous; they're basically only counting the parts of it that are animated and discounting all the live action timespan. Mildly triggers me.