Most critics come away unsettled, and the praise clusters on how Hitchcock stages the attacks. The birds gathering outside the school are picked out more than once as the film’s most frightening passage, and several reviews note how much of the dread comes from the refusal to explain anything. The electronic soundtrack of bird noise, rather than a conventional score, is singled out as part of what makes it so eerie, and the film is described as darkly comic before it turns nasty.
The spread is wide, and the dissent is old. The two reviews written on release are the two negative ones: Variety finds the human drama thin and the romantic subplot left dangling, and The New Yorker goes further, arguing the film never builds suspense and finding the sadism of the attacks repellent. Later critics are markedly warmer, and one review reads more as description than verdict.