The intense paranoia present throughout this fantastically-done science-fiction/horror movie only add to the final product - one that is, at any point in time, a thought-provoking and terrifying film.
The film, in which pod people begin taking over the citizens of a moderately-sized California town, highlights how, even in suburban, run-of-the-mill locations, terror and panic can spread. While potentially anti-Communist propaganda (which would be the single flaw of the film, were it intended), the struggle for individuality and love versus complete conformity is still thrilling to this day - plenty of the scenes still stand strong even now, such as Kevin McCarthy's character running down the highway, screaming for people to listen to him, or the chasing of McCarthy and Dana Wynter's characters by the pod people that used to be their friends.
Telling the story in the past-tense, and book-ended by events that take place almost a day after the core of the film, was a somewhat questionable choice, and one could certainly argue the movie would be better (if not more downbeat) had the movie ended without the final framing sequence (in fact, that's exactly how the original creators had preferred it to end), but I still find it an acceptable finale.
Invasion of the Body Snatchers is a fantastic film, well-worth the highest honor among horror films for both the decade of the 1950's and of all-time. If I had one complaint, it would be that occasionally, I felt it became a bit too melodramatic - luckily, if that's the case, it doesn't happen that often, and shortly afterward, we're back to action of some form or another. In short, this is a great film. 9.5/10 (rounded down to 9/10 to fit site's format).