Scrambled Face’s review published on Letterboxd:
Dick Randall and Steve Minasian produced three ridiculous European slashers in the 1980s, and considering the sheer trashy joy conjured by Pieces and Don't Open Till Christmas, I had to complete the "trilogy." Slaughter High is easily the drabbest looking and most conventional of the batch, but despite the three writers/directors credited here, the Randall/Minasian lineage proudly shows in the through line of careless construction and silly/creative death scenes, all of which keep it weird enough to maintain interest.
Slaughter High hinges on the old "slasher at the high school class reunion" routine, said slasher being the class geek (Simon Scuddamore) who was horribly scarred during the extra-long introduction, wherein his loathsome classmates' bullying escalates from nude swirlies to too-powerful pot to premeditated arson. The reunion is only for about ten people (all Brits attempting American accents, with varying success), it takes place in the middle of spring (April 1 being the key date) and the school appears to be long-abandoned when they arrive. Since they still haven't noticed that class queen Caroline Munro is about a decade older then the rest of them (not a plot point, BTW), it makes sense that these people would sit outside for several hours before deciding to break in, pair off to have sex after discovering their pals murdered or keep returning to the same locker room where the whole mess began. As for the Lovecraftian logic of the building's layout, how the killer nerd got acid to pour out of the bathtub faucet, why the high school even has a bathtub, or a fully-dressed bed big enough for two people, or a tractor... you're better off not asking.
It may seem facetious to invoke the professionalism of Pieces, but at least that film never broke my #1 rule for low-budget horror: no extended sequences where you can only see darkness. Slaughter High does not fare as well in that department, at least not on the murky U.S. DVD, and combined with the predictable school slasher framework, its unimpressive visuals make this a more mundane experience than the previous lunacies from Randall (who phones in a cameo!) and Minasian. That said, the gore is nice, the tone is fun, and the strange, thoughtless details keep you guessing, right up to the trademark nonsense ending. At the very least, this is a much better April Fool's Day slasher than the actual April Fool's Day.