I don't often read fiction, but when I do, it's because the book is highly recommended. In the case of The Hitchhiker's Guide To the Galaxy, there are just too many people who love this book for me to have ignored it any longer.
Sci-Fi is usually a hit or miss proposition for me. In this case, it was a hit. I really enjoyed Adams' clever style of writing. The story was also good, and the anecdotes within the book make you think about your biases and perceptions.
Now that I've read it, I can see that quite a few pop-culture references I never quite understood (without knowing it) were taken straight out of this book.