The story, as you likely know, follows proto-feminist Jenny Fields who decides to have a child with as little help from a man as humanly possible in the mid-1940s. Her child, Garp, grows up wanting to be a novelist, but his attempts at serious writing becomes somewhat overshadowed by his mother's bestselling anti-lust manifesto. Much of the story centers on Garp's struggles to be a good husband and father to his own children.
A lot of the details and depth of the novel obviously got squeezed out in order toget the film down to it's longish 136 minute running time. We lose the long passages of Garp's writing, their trip to Austria, and scenes from the 70s swinging lifestyle, but most of major events in the novel make some sort of appearance in the film. With the novel fresh in my mind, I felt a bit disappointed by the screenplay, but I'm not certain any adaptation would have truly satisfied me.
It was one of the last few films directed by the great George Roy Hill, who made Butch Cassidy and the Sundance Kid, The Sting, and (one of my personal favorites) A Little Romance. I've yet to see a bad film by him and this one was no exception. Glenn Close and John Lithgow (playing a transsexual ex-football player) both give absolutely first rate performances for which they received much deserved Oscar nominations.