Them/YMMV


 * Special Effects Failure - Compared to today's slick CGI, the ants look dated, but the giant models were impressive for their time, albeit slow-moving. One reason most of the following giant-thing movies were so bad is that pretty much all of them used clumsy super-imposed images to serve as the monster.
 * Nothing Is Scarier - Much of the beginning of the film shows only the aftermath of the ants' attacks. We see only the damage they have caused and a few bodies, one of which is filled with acid and chewed to bits. This helped build up their menace prior to them turning up on screen.
 * Hell Is That Noise - The noise that the ants make is extremely chilling. It also doesn't help that in the place I was growing up in, there were some tree frogs that made that exact same NOISE! Many sleepless summer nights went by and lets just leave it at that.