As of January 19, 2008, review aggregate website Rotten Tomatoes reported that 78% of critics gave the film positive write-ups, based on 109 reviews.[31] At the website Metacritic, which assigns a rating out of 100 to each review, the film has received an average score of 61, based on 32 reviews.[32]
Todd McCarthy of Variety called the film an "old-fashioned monster movie dressed up in trendy new threads", praising the special effects, "nihilistic attitude" and "post-9/11 anxiety overlay", but said, "In the end, [it's] not much different from all the marauding creature features that have come before it."[33] Scott Foundas of LA Weekly was critical of the film's allusions to the September 11, 2001 attacks and called it "cheap and opportunistic". He compared its "stealth" attempts at social commentary unfavorably to the films of Don Siegel, George A. Romero and Steven Spielberg, saying, "Where those filmmakers all had something meaningful to say about the state of the world and [...] human nature, Abrams doesn't have much to say about anything."[34] Manohla Dargis in the New York Times called the allusions "tacky", saying, "[The images] may make you think of the attack, and you may curse the filmmakers for their vulgarity, insensitivity or lack of imagination", but that "the film is too dumb to offend anything except your intelligence." She concludes that the film "works as a showcase for impressively realistic-looking special effects, a realism that fails to extend to the scurrying humans whose fates are meant to invoke pity and fear but instead inspire yawns and contempt."[35] Stephanie Zacharek of Salon.com calls the film "badly constructed, humorless and emotionally sadistic", and sums up by saying that the film "takes the trauma of 9/11 and turns it into just another random spectacle at which to point and shoot."[36] Michael Phillips of the Chicago Tribune warned that the viewer may feel "queasy" at the references to September 11, but that "other sequences [...] carry a real jolt" and that such tactics were "crude, but undeniably gripping". He called the film "dumb", but "quick and dirty and effectively brusque", concluding that despite it being "a harsher, more demographically calculating brand of fun", he enjoyed the film.[37]
Marc Savlov of The Austin Chronicle calls the film "the most intense and original creature feature I've seen in my adult moviegoing life [...] a pure-blood, grade A, exultantly exhilarating monster movie." He cites Matt Reeves' direction, the "whip-smart, stylistically invisible" script and the "nearly subconscious evocation of our current paranoid, terror-phobic times" as the keys to the film's success, saying that telling the story through the lens of one character's camera "works fantastically well."[38] Michael Rechtshaffen of The Hollywood Reporter called it "chillingly effective", praising the effects and the film's "claustrophobic intensity". He said that though the characters "aren't particularly interesting or developed", there was "something refreshing about a monster movie that isn't filled with the usual suspects."[39] Lisa Schwarzbaum of Entertainment Weekly said that the film was "surreptitiously subversive, [a] stylistically clever little gem", and that while the characters were "vapid, twenty-something nincompoops" and the acting "appropriately unmemorable", the decision to tell the story through amateur footage was "brilliant".[40] Roger Ebert in the Chicago Sun-Times wrote that the film is "pretty scary at times" and cites "unmistakable evocations of 9/11". He concludes that "all in all, it is an effective film, deploying its special effects well and never breaking the illusion that it is all happening as we see it."[41]