Clearly inferior to the anime. In no department does it compare. Atmosphere, plot, gore, characterisation and acting are all worse. I won't go so far as to say I was bored, but it didn't hold my attention as firmly.
It's basically the same story, though. (Apparently important story points change in every adaptation, incidentally, be it the anime, the manga or the original novel. Different people die in different ways, etc. I haven't read the novel, though, so my only point of comparison will be the P.A. Works anime.) 26 years ago, in 1972, a girl stayed in Class 3-3 despite being dead. That's how everyone saw it, anyway. In this film's version of the flashbacks, they put a doll on her chair.
Since then, in certain years, bad things have happened. Further details are a mystery for the audience to discover.
The film feels like an understated, grounded J-horror. Ringu rather than Ito Junji, if you like. The tone is "drab reality". (That's the default setting of Japanese cinema in general, although there are lots of counter-examples.) This film mostly avoids flamboyance, instead giving us a realistic school in a realistic small town. The budget doesn't look to have been particularly high. The cinematography is no-frills. It looks like a school because they filmed in a school. This is a long, long way behind the anime, which was drenched in style and crafting atmosphere with pretty much every shot in every episode.
Well, except for the finale. That's letting its hair down, but again less so than the anime (which went completely batshit).
There's CGI, of course. There's even a tiny, grudging amount of gore, but so little that the film's managed to include a bloodless decapitation. (The phrase to use in such circumstances should be "arterial gushing".) This film's first death penetration shot looks like plasticine. Another person gets stabbed through the forehead with almost no blood loss. The film sort of manages to get away with it, but it's still not very good. One might wonder if they'd been trying to create a family-friendly horror film, but in fact Tomoko tells me Japan's got strict about that kind of thing lately.
In fairness, though, one death was quite funny. Amusingly there also happens to be a chainsaw lying around during the finale. (It doesn't get used, but one still appreciates the thought.) The film's still had its teeth pulled, though.
Then we have the characters. This is actually my main objection to the film. Gore is dispensable, but here they've established an anti-acting house style and sidelined all the teenagers bar Kouichi and Mei. Almost no one seems to be able to act. A couple of the older cast members can stretch to it (e.g. Mei's mother, Kouichi's grandmother), but Kento Yamazaki is empty as Kouichi and no one else is taking up the slack.
I don't blame Ai Hashimoto so much. Her character's meant to be withdrawn and unsociable. Also this is partly a stylistic choice, with the anime similarly portraying a world where everyone's standoffish, distant and slightly chilling. However the film mostly just gives the impression of having cast wooden actors. (I enjoyed the moment when the entire classroom went still, though.)
The storyline is simpler. Mostly the simplification works, but there's less misdirection in the first act. That's a shame, I think. It also made me think that the story might feel far stronger if it weren't for Mei's eye, which theoretically applies to the anime too, but there never occurred to me.
This isn't a terrible film, but it lacks bite. It drifts. It's not filling its boots. The story it's telling is quite interesting and it's always sort of okay, but it's weak. I quite like the 2012 epilogue, partly because it has no equivalent in the anime. Otherwise, no. Watch something better instead.