The Fountainhead was first book by Ayn Rand I've ever read. As it changed my life significantly it might change yours as well.
When one reads the book one might think "alright Rand we've got the point, stop repeating it". I would say it's done on purpose so everybody gets the point, though I have seen many different opinions on Ayn Rand's Objectivism on the internet and certainly not everybody got it. At first I thought it might be good idea to read some critics (especially the other side of my own opinion) but mostly it's just barking, sensless or worse - religion barking.
What is the book about? In very short it's about individualism against collectivism, a man against society as whole. The story answers questions like: Should society stand above individuals?
If one decides to know more about Objectivism, the philosophy that Ayn Rand pushes ahead, one finds this book is just a glimpse of the philosophy of reason.
By the way there is movie the Fountainhead (1949) (Rand was involved in the production) that seems to me not as good as the book although it says what ought to be said, it's just running too fast comparing the book version.
You could even find Roark's final speech (main character played by Gary Cooper) googling around.. Anyway I would cartainly read the book first.