Be forewarned, there is basically no dialog in this film. This isn't a problem for me, but with American audiences today that won't even deal with subtitles... I'm aware not everyone might not be up for an hour of silence.
You do however get to see some great dinosaur/etc stop-motion effects, Harryhausen-quality stuff. There's also the best use of an iguana to simulate a dinosaur that I've ever seen, an effect that I never expected to see done successfully.
This is also the film that this much-used clip of a claymation t-rex fighting a tricerotops comes from. Very good, classic stuff.