"By the time Monster A-Go Go gets close to its ending (or, to put it more accurately, the point where the film runs out), you're not even sure if you're still watching a movie, instead of the result of someone pointing a camera in a random direction just to see what it happens to pick up."
- Albert Walker, The Agony Booth, 2003.

"Monster A-Go Go, for all its theoretical entertainment value, defiantly manages to claim a slot for itself in the ['astronaut becomes monster'] field by virtue of its finale, in which Lewis devises a mysterious 'twist' as a smokescreen for the fact that the film actually has no ending whatsoever ('uncompleted' means uncompleted!). Southern drive-in audiences were left to chew on this as the drive-in double bill came to an end."
- Shane M. Dallmann, Video Watchdog, 2003.

"Another one of those ya-gotta-see-it-to-believe-it! numbers...this flatfooted foolishness has all the charm of a 70-minute rectal examination."
- James O'Neill, Terror on Tape

"It's a familiar yarn about an ill-fated astronaut who returns to Earth as a 10-foot-tall, 400-pound, pizza-faced monstrosity...who turns anyone he paws into an overgrown and very lifeless PRUNE! (Even if a "dead" actor can't quite hold a twisted grimace for his postmortem closeup). Bikini'd babes jiggle for their lives as this beast lumbers hither and yon, miraculously managing to evade capture. Marvel at the much-too-tiny cardboard space capsule and, most of all, behold how Lewis adeptly handles an actor's amazing-disappearing toupee."
- G. Noel Gross, CineSchlock-O-Rama, 2001.

"About the only good thing in the film is the zombie stomp theme song, whose driving bass mimics the throbbing in your temples from trying to decipher what the Sputnik is going on here. No matter how it was created or the resulting pseudo coherent continuity of the film, Monster plays like a disjointed carnival sideshow, complete with an oversized human stick figure and various other non-acting human oddities."
- Bill Gibron, DVD Verdict, 2002.

"Probably sourced at random from an anonymous, perverted Mad Libs collection."
- Joseph A. Ziemba, Bleeding Skull, 2007.

"Hilarious from start to finish and obviously geared toward the bottom half of a double bill, this has the feel of a flipside of a '50s single where they didn't care what the hell happened."
- Andrew Hershberger, Mania.com, 2002.

"How bad is it? Suffice it to say that Herschell Gordon Lewis was brought in to 'fix' the results."
- Charles Kilgore, editor of Ecco Magazine.

"Monster A-Go Go is a train wreck of a movie that had such a low budget that someone had to mimic the sound of a telephone ringing. (Badly too, I might add.) I mean this is Manos: The Hands of Fate bad. The plot, what there is of it, involves a space capsule that crashes to Earth, and soon after a tall monster starts running around killing people. It doesn't sound too bad, but so much of the story happens off screen, the viewers are only cued in by the narrator, that this movie easily falls into the "abominably horrible" category."
- John Sinnott, DVD Talk

Compiled by Bret Wood