Ray Harryhausen's special effects were state-of-the-art at the time. The special effects were like peanuts: you loved them but they made you want more (my apologies to those of you with peanut allergies; please substitute "chocolate" or "donuts" in my simile). The story is coherent and well-told, although there was too much comic relief, although excessive comic relief was frequently found in science fiction movies back then. It still happens today, as in the terrible translation of "Starship Troopers" from novel to film. Back then, this country was in the midst of the Cold War, and I think film-makers worried about scaring people too much (a la the radio broadcast of "War of the Worlds"), so they inserted unnecessary comedy.

Anyway, I liked this movie as a kid, and your kids will probably like it too, although they're spoiled now by hyper-realistic special effects and excessive action. Buy it or rent it, and have a ball. Adults might find it too cartoonish, as I did when I saw it again recently.