Ultimately it's all too predictable.
What are people saying?
What are critics saying?
Before it's done, Hello Mary Lou has touched most of the bases, flirting with taboos (incest, locker-room lesbianism, fingernails on the blackboard) and purloining effects from the Nightmare on Elm Street series. It's a badly made film, as awkward as can be, and long stretches of it make no sense whatsoever. Nor does it manage, as the better slasher films do, to re-create a high-school milieu of even passing authenticity. [21 Oct 1987, p.D5]
Los Angeles Times by Kevin Thomas
The "Blue Velvet" of high school horror pictures...Certainly, it's not on the deeply personal, highly idiosyncratic artistic level of the David Lynch film, but it is a splendid example of what imagination can do with formula genre material.
Washington Post by Richard Harrington
Hello Mary Lou: Prom Night II may be derivative, but for the most part it's clever enough to trade on its sources with humor and class. It's "Peggy Sue Lives on Elm Street," with dollops of "Carrie," "The Exorcist" and a half dozen other genre stalwarts.
The New York Times by Vincent Canby
Hello Mary Lou has nothing much to do with the original "Prom Night" (1980), except that it's somewhat more entertaining if female nudity, bizarre violence and comically deadpan special effects amuse you...Bruce Pittman, the director, and Ron Oliver, who wrote the screenplay, have constructed the movie as if it were a gourmet banquet for toddlers. From the first course to the last, it's all ice cream.