How bad is it? It's reprehensible garbage, but competently made.
Should you see it? If women's prison films are your thing, by all means. But don't admit it. If you admit to seeing it, don't say you liked it. And if you like it, don't say it publicly (like in a blog).
Believe it or not, "women in Nazi prison camps" films are their own genre. There's "Love Camp 7," "S.S. Experiment Camp" and "Gestapo's Last Orgy," for example.
This is one of those rare films where it's lack of production quality actually makes it more effective. The film is generally underlit, making it seem grittier and perhaps more authentic. Most of the serious gore is left off-camera (when it isn't, it's not well done) and this causes one to imagine far worse than if it were explicitly shown. Star Dyanne Thorne's makeup is heavy to the point of being a mask, making her on a par with any hockey-masked slasher in the 1980's. It's impossible to find photos that show the charisma of the main character; here's the best available that have no nudity:
Thorne was 42 when this film was made (perhaps in bust measurement, as well as age) and causes the viewer to think she must've been something to see when she was younger. [Not really the case - I've seen "Swinging Barmaids" and "The Erotic Adventures of Pinocchio" (It's not his nose that grows), made when she was younger. She was fetching in her brief moment in my favorite episode of the Star Trek TV show, "A Piece of the Action," however.] Breast fetishists get a double dose of what they seek because of the brief appearance of Uschi Digart, as the woman killed in the pressure chamber.
The most memorable scene for me is the woman strung up while standing on a block of ice; she freezes and the melting tightens the noose. It's done on top a table, as entertainment for men having dinner. Yeah - the film's that classy.
The two things the film has going for it (no, not breasts) are the sets, which turn out to be the same ones used for the TV show "Hogan's Heroes" and the unrelenting seriousness of tone, which is sadly lacking in the follow-ups "Ilsa: Harem-Keeper of the Oil Sheiks," "Ilsa: Tigress of Siberia" and "Ilsa: The Wicked Warden." "Harem-Keeper" has one good gross-out joke and even more nudity. "Tigress" has better cinematography, but is dull. "Wicked Warden" is a by-the-numbers women's prison film by Jess Franco, also released as "Ilsa - the Ultimate Power," "Wanda, the Wicked Warden" and "Greta the Torturer."