To be fair, I didn't even watch the whole movie. I just don't think it's a book that is easily adapted to the screen. The book is quite cerebral and the pace is slow and that doesn't translate well into a feature film. Maybe I'm jaded, having just read the book, but all I could think throughout was how much was being left out - important things that gave life to Ripley's character. The movie didn't capture the almost sadistic pleasure Tom Ripley takes in scamming people - his sociopathy. Instead, Tom only appears to be an opportunist.
Maybe if I had seen the film before reading the book I would have appreciated it more, but I'm pretty sure I still wouldn't have thought it was particularly good. However, based on a recommendation from a friend, I am going to watch Ripley's Game, which has gotten better reviews. I just don't know if I'll watch before, or after, reading the book.