My knowledge of John Williams' film scores is far from complete, but I would bet that if you wanted to find the score in which the maestro's tongue was planted the most firmly in cheek, it would probably be this one.
Bombast. Volume. Cannons. The main theme dominates the soundtrack, and Williams turns the volume up to 11 in an effort to keep up with the artillery-fire, explosions and fighter planes from the Spielberg film. It's raucous, and intentionally so. Whether you enjoy it depends on how seriously you want your soundtracks to take themselves.
My opinion: it works, but actually the theme makes the best impact on the Williams Greatest Hits CD. There it provides a nice counterpoint to the more serious side of Williams in "Stepmom", "Saving Private Ryan", and yes, "Jurassic Park".
The rest of the 1941 soundtrack is not quite as memorable, but it contains (1) some nice period elements, and (2) some very Williams-esque romantic moments (check out "To Hollywood and Glory"). Oh, it also contains carnival-style music.
This score came at one of Williams' peak years, so even if the inspiration does not quite meet a "Superman", "Star Wars", or "Raiders of the Lost Ark", the execution is marvellous. Listen to a track like "The Invasion" and you will hear elements that would be at home in one of these movies.