Metacritic reviews

It all adds up to a surefire cult film in the making.

Will you like this film? Yes, probably, if you like monster and horror movies. The movie occupies familiar ground, but it has a freshness and winsome humor to fit it, and Craven moves confidently through the three related genres he's stealing from (monster movies, mad scientist movies, and transformation movies in which people turn into strange beings). There's beauty in this movie, if you know where to look for it.

Swamp Thing isn't completely successful at banishing the old corkers and stereotypes, but it's a harmless, watchable comic-book thriller, refreshingly suitable for kids of almost any age.[10 May 1982, p.C2]

Craven tries to do this 'veggie-man' horror in a suitable DC Comics style; and with Louis Jourdan as arch-villain 'Arcane', not to mention Adrienne Barbeau (Mrs John Carpenter) as the Thing's object of desire, he's definitely on the right track. At other times, the picture is right off its trolley.

Swamp Thing has many dubious qualities, but it clearly isn’t a piece of product tested and polished to a blinding gleam, and the world is duller for not letting oddball efforts like this slip into theaters once in a while.

Wes Craven's Swamp Thing wants desperately to be funny and, from time to time, it is. However, you might wish it would trust the audience to discover the humor for itself.

Deserves - to be "watched" with steam on the windshield and passion in the air. When the monster in a monster flick packs all the fearsome wallop of an overripe avocado, one needs some diversion.[8 June 1982]

Although SWAMP THING was definitely aimed at a different audience than THE HILLS HAVE EYES, Craven fails to capture the gothic quality of its comic book inspiration--which had some genuinely frightening and grotesque moments. Instead, the whole thing is merely silly and not much fun.

Short on thrills and laughs...Craven tries in vain, through old-fashioned characters and dialog, to re-create the ’50s B-monster movie. The film’s only asset for adult audiences is Barbeau, who is thoroughly believable and a feisty, rough ‘n’ tumble heroine, able to beat up most bad guys or outrun them through the swamp.

Craven seems to have set out to make a bad movie, and he's succeeded.