Which of the acknowledged clics have you read under duress, only to discover that it was...?

As a high school student, many years ago, it was Charles ens' Great Expectations. At the beginning it was difficult to get interested in, and a lot like swallowing mineral oil; I just couldn't choke it down. However, after repeated attempts I did finally succeed, and suddenly found to my great surprise how wonderful the novel was written, filled with wonderful and appealing characters, each with their own story, and told by a masterrful author. All in all, it became a book that I couldn't put down, and enjoyed thoroughly.