For the most part, I think that the film portrayed most of the novel's characters perfectly, such as Richard Attenborough as John Hammond, although he could've been a little greedier and darker, and Wayne Knight as Dennis Nedry. However, certain characters I don't think represent the same characters nearly as well, such as Robert Muldoon. I love Muldoon in the film, played by Bob Peck, but I don't feel like he's the same character as the novel Muldoon. Robert Muldoon is more like an aged hunter, 50-55 years old, with a steel-gray mustache and an alcoholic addiction, but brilliant anyhow, and continously hunting and serious. I am most reminded of Muldoon from the novel when I see Jaws, because Robert Shaw's character, Captain Quint, strikingly resembles Muldoon. He has a gray-mustache and brilliant blue eyes, and a drunken, hatred driving attitude from his past, just like Muldoon from the novel, growing up under his father in Nairobi.

Quint Muldoon

Personally, this is how I picture Muldoon in the novel