BFI Screen Online says,
The dominant theme of Kes is the way in which the education system stifles the talents of many young working-class children, offering them little choice but to follow the narrow path laid out for them by an industrial capitalist society which sees them as fit only for unskilled manual or office work.Criterion says, "Named one of the ten best British films of the century by the British Film Institute, Ken Loach’s Kes, is cinema’s quintessential portrait of working-class Northern England." Slant Magazine gives it 4 out of 5 stars, says, "If the concept of art for the masses means anything, it finds a masterpiece in Kes" and closes with this: "An axiom of unsentimental storytelling, Ken Loach's masterful second feature represents a critical turn away from the popularized kitchen-sink realism of the 1950s and '60s and toward a more improvised and unpredictable narrative style."
Bright Lights film journal says,
It’s mature not only in its objective and unsentimental treatment of a flawed boy and his hostile environment, but also in its general cinematic form, with multiple asides and deviations from the primary narrative. The film frequently follows characters other than Billy for a considerable time, but never too much, just enough for Loach to establish Billy’s world and to tell us a little about this region and where these people are coming from. In the end, though, what truly matters are Billy and Kes, this boy and his bird.TCM has an overview. Roger Ebert gives it 4 out of 4 stars and says, "The film has a heartbreaking humanity." Rotten Tomatoes has a critics score of 100%.