Critical response
This film received mixed reviews from critics. Review aggregation website Rotten Tomatoes gives the film an approval rating of 53% based on 129 reviews, with an average rating of 5.8/10. The site's critical consensus reads, "City of Ember is visually arresting, and boasts a superb cast, but is sadly lacking in both action and adventure." On Metacritic the film has a score of 58 out of 100 based on 27 critics, indicating "mixed or average" reviews. Audiences polled by CinemaScore gave the film an average grade of "B+" on an A+ to F scale.
Stephen Holden of The New York Times said that the "talents of Saoirse Ronan, the brilliant young actress from Atonement", were "wasted in the science-fiction juvenilia of City of Ember", though he added, "Most of the time, however, it's a whiz-bang kid's film with neat gadgets and sound effects and an extended chase and escape sequence through underground rivers and tunnels. At only 95 minutes, the movie feels as though it had been shredded in the editing room. [...] The best things about this are scenes of the ominous grinding machinery of the kind found in railway yards, as well as several zany gadgets worthy of Rube Goldberg. The wittiest is a primitive telephone-answering machine that resembles the do-it-yourself hi-fi kits assembled by audiophiles in the early days of stereo [...] Tim Robbins is also on hand as Doon's earnest, secretly rebellious father, who spends his days tinkering with exotic inventions [...] But not to worry: the boundless resourcefulness of two curious, clean-cut adolescents full of gee-whiz enthusiasm may lead humanity back into the fresh air and sunlight."
Justin Chang of Variety also gave the film a mixed review, calling the film "A fabulously designed underground metropolis proves more involving than the teenagers running through its streets in City of Ember, a good-looking but no more than serviceable adaptation of Jeanne Du[P]rau's 2003 novel. Director Gil Kenan's disappointing live-action follow-up to his enjoyable toon debut, Monster House, shows promising flickers of the visual invention throughout, but the dramatic sparks fail to ignite in this simple-minded exercise in juvenile dystopia." Chang also observed that the characters represent "English-speaking, predominantly Caucasian humanity."
Irv Slifkin for Video Business wrote, "this lavishly designed adventure saga from director Gil Kenan... plays like Terry Gilliam's Brazil — for beginners". He praised the "secret escape plan hidden by Ember's founders" and "impressive technical work," concluding that there were "drama and sometimes lethargic pacing, but there's enough here for middle- and high-school kids to think about and marvel over."
Cinema Blend's editor-in-chief, Katey Rich gave the film 2.5 of 5 stars and said, "The City of Ember belongs to one of the best and most enduring genres of children's films, in which smart kids stand up against the ignorant and aloof adult world and have a big adventure in the process. It also throws in a fantastical city, replete with whiz-bang inventions and secret societies. It's a mystery, then, that all the happy elements only add up to a big mush, a dull adventure, and a contrived fantasy. Saoirse Ronan is a fantastic heroine, but the story and the rest of the cast can't keep up with her lively pace." She added that "director Gil Kenan seems hellbent on just driving the narrative forward. The movie clocks in at an acceptably short time for a kid's movie, but so much gets lost or glossed over along the way. Ember itself is fascinating, an intricately detailed set that, like Diagon Alley or the Star Wars cantina, you'd like to take a few hours to wander around in. But so many questions about the city are left unanswered... You get the feeling that Jeanne Du[P]rau's book got into this stuff, while the movie never seems to have the time."
TV Guide gave City of Ember 3.5 out of 4 stars, stating, "A fun and moving family film with a subtly dark feel rarely seen in kids' movies since the '80s, City of Ember succeeds despite its shortcomings, not only because of its fun and inspiring story, but because most of its flaws are things kids won't notice anyway. [...] [T]he story spins into a classic fable; the ignorance that seemed so blissful shows it's just one half of a coin, where the other side holds apathy and hopelessness. The moral might well be lost on kids, but for adults, it's compelling — all the more so because we like the good people of this dying city." This reviewer praised the "series of exciting adventures" and argued that "Lina and Doon's vigilant sense of hope is, in the end, incredibly inspiring and extremely pertinent... It might be a staple theme in family films, but the City of Ember is a useful reminder about the power of the human spirit to triumph where our own hopelessly broken systems have failed. It's a message that the filmmakers didn't take for granted — and that hopefully viewers won't either".