I know there's really no point in arguing about matters of taste, but I've seen the film and read the book, and vastly prefer the film. Kubrick's film is a work of genius, if you ask me, and the book was mediocre at best. In my mind, it read like a bad novelization of the film (even if it wasn't written as one.)

And no, you absolutely do not need to read the book to have a clue as to what is happening in the film. As Ebert points out, you just need to sit back and watch, and enough will be revealed.