The film, which premiered at Venice, follows a mute cleaner at a U.S. government aerospace facility who bonds with an amphibious creature.

Thanks to the lightness of touch and dedication of all involved, Rooney said, the romance between a woman and a sea creature transcends its genre roots: "A lesser filmmaker might have rendered all this as simply a gender-flipped Splash, but del Toro's attention to nuance makes it an utterly transporting fable with very real stakes and convincing political overtones … this meticulously crafted jewel is del Toro's most satisfying work since Pan's Labyrinth."

The Playlist's Jessica Kiang agreed, calling the movie "the greatest showcase for del Toro’s mercurial, dark-tinged but delightful sensibilities, and his best film since Pan’s Labyrinth." She continued, "There is unmistakable, idiosyncratic care poured into every frame of The Shape of Water, saturated with del Toro’s offbeat compassion and looping, pattern-recognition intelligence."

For The Guardian's Xan Brooks, it was even more impressive; the "sweet, sad and sexy" movie was, he suggested, del Toro's best feature yet.

"It feels less of a fevered artistic exercise than his other recent work; more seamless and successful in the way it orders its material," he argued. "Yes, del Toro’s latest flight of fancy sets out to liberally pastiche the postwar monster movie, doffing its cap to the incident at Roswell and all manner of related cold war paranoia. But it's warmer and richer than the films that came before."

That's something that Screen International's Fionnuala Halligan also touched on in her review. Calling the movie "del Toro at his most poignant and sweet, eschewing the harder edges of horror and releasing a torrent of warmth into a precisely calibrated setting," she wrote that, "while shaping a classic creature movie, del Toro has focused on its heart, and the result is intensely humane. If there's a spirit it embodies, it's that of Woody Allen in his Purple Rose of Cairo days, crossed with the Universal Creatures who fled hatred and persecution, and this Venice-Toronto feature should have a wide, more mature appeal because of it."

With particular praise being paid by almost all critics for not only the performances from Hawkins, Octavia Spencer and Doug Jones — the latter playing the mysterious creature Hawkins' character falls in love with — but also the score from Alexandre Desplat, it's clear that The Shape of Water has a particularly wide appeal even to those unaware of the genre history del Toro is playing with.

"[I]t’s a film that makes you feel a lot," wrote The Daily Beast's Marlow Stern. "But overridingly you feel lucky — lucky to be watching it, lucky that something so sincerely sweet, sorrowfully scary and surpassingly strange can exist in this un-wonderful world, and desirous of hanging on to as much of its magic for as long as you can after you re-emerge back onto dry land."

Along similar lines, Collider's Brian Formo called the movie "an immense achievement" with particular resonance for today's audiences, suggesting that it "reinforces a faith in humanity set in a time where tolerance of other races, nationalities, and non-'family values' love was volatile … You'll leave the theater with a lighter air in your lungs. It's delicate and it's timely."

Domestic audiences will get to experience the movie for themselves when The Shape of Water opens Dec. 8.