Film Actually Pretty Good On Its Own Terms
To enjoy this movie, you must first accept that while the film is nominally a sequel to The Rocky Horror Picture Show, it bears no resemblance to it and features nothing from it aside from Brad and Janet, the town of Denton, and the Hapschatts. Once you accept this, you'll probably find that it's actually pretty good for what it is. (Despite this, though, one can make a case that the events of the film take place after Rocky Horror. But that's another story.)
The film, in comparison to Rocky Horror, is far more... "normal". Where the first film was an insane, campy tribute to 50s B-movies, this does a complete 180 in terms of what it is - a satire on television, and in that respect it succeeds as a film. In many ways the film is incredibly prescient; in our modern age it seems like the film's idea of a town turned into a TV studio is possible. (Of course, it'd probably be something Internet-related if they made it today.)
It is also more "normal" as a musical. Unlike Rocky Horror, which was mostly sung - especially by the end - this intersperses the musical numbers with a lot more dialogue than was in the first film. And I will mention that there are quite a few musical numbers that stick up with those in Rocky Horror - "Denton, USA," "Bitchin' in the Kitchen," "Thank God I'm a Man," I could go on...
As a sequel to Rocky Horror, Shock Treatment fails miserably. However, as its own thing, it's a genuinely good piece of cinema, and if you actually wish to check it out, do so. You might actually enjoy it.
Film Look out, mister, don't you blow your last resistor for a critic that'll mystify ya...
Rocky Horror was lightning in a bottle. However, this follow-up stands alone pretty well as an effective, disturbing piece of commentary.
Brad and Janet (recast) are preyed upon by a television conspiracy. Brad is committed in a TV asylum after Janet expresses boredom on a quiz show. Brad is "cared" for by fraud doctors while the various TV hosts and their executive seduce Janet into stardom "for Brad's sake". News anchors Betty Hapschatt and Oliver Wright uncover the conspiracy's reach and work to free Brad and Janet. Like the previous film, Brad wants to remain himself while Janet is easily led to new places, but her new self is unambiguously negative here. The cast is a mix of "old characters, new actors" and "new characters, old actors", but performs well. The previous story has little, if any impact here, so just know that.
It's the surreal commentary that really shines. The town of Denton is possibly literally consumed by its TV studio, with some people living their lives on a TV show and the audience staying in their seats to sleep in a tangled heap. It's unnerving yet authentic how easily swayed the town is to what's shoved through a screen, and there's commentary about celebrity abuse and exploitation and fame's dangers as well. The finale, while optimistic, also happens to be genuinely chilling in the conspiracy's final bow, and the movie very effectively ramps up the horror in uncovering how strange and powerful it truly is. Rocky Horror was parody. This movie is horror. It also unwittingly predicted reality TV and influencer culture.
The music is expectedly fantastic, since it's Richard O'Brien's work.
The film is a little messy and hard to grasp at first, but everything falls into place and is very effective by the end. It has qualities superior and inferior to Rocky...because it's a different product. Don't weigh it the same way. I think it mostly succeeds at its vision, and often, superbly.