I went in with high expectations knowing this was based on "Drifting classroom", Which I've yet to read, but that I know heavily influenced one of my favorite anime, Sonny Boy, with its premise of a school being transported to another world. Sonny Boy, i can Highly recommend, this however was a bit of a slog.
I strongly feel this should have been a 30 minute show, with maybe a few extra episodes, most of the plots feel stretched and theres lots of looking at the same scenery.
My other 2 criticisms is the heavy reliance on romance and unexplained supernatural phneomena. The romance just doesn't do it for me, its very slow and the romantic tropes of the era did not age well. The strange phenomena just felt like a plot contrivance, and I'm curious to check out the manga (Which is very different, more horror, and focuses on younger kids i think) and see if maybe it better explains some of these scenarios.
Now, as for why i gave this a 6 and no lower, I have 2 main reasons:
1. Some of the characters are really endearing and well acted, and the scenario itself is a goldmine, its just not mined very well IMO. The plot lost its luster for me around the 7th or 8th episode, there were still a few nice moments, but i really struggled to finish it.
2. The environmentalist message of the show is laudible, there should be more media about subjects like this tackled in really engaging ways so we can convince people to make changes.
Ultimately, if you like or can tolerate cheesy romance, and some slow pacing, and you don't need the sci-fi/fantasy elements to be realistic, you might get more out of this than me, but if you don't some real strong interest, I can't recommend it, especially with how hard it was to find.