This is an article from the British Film Institute, written for the film's 50th anniversary in 2018.

On a personal note, I went and saw the cleaned-up print they released to theaters for the 50th (remember theaters?), and it holds up amazingly well for a movie from the late 60s. In some ways it has more teeth than modern zombie fare, because it's not about "zombies". The image you have in your mind when you see that z-word had not yet solidified in the public mind. These are just folks, recently back from the dead, hungry and not taking no for an answer.