If I had a nickel for every time I have been told this in the past 35 years or so, I'd be a very rich man. First off, I do not read fictions (I doubt I've read 25 of them in my lifetime).
The Fountainhead was the longest fiction I've ever read. But that book captured me right up front with a kind of unimaginable mystery, its description of a new kind of architecture. I do not think I would have gotten past page 20, had I had reason to adequately believe that it was Frank Lloyd Wright's architecture she used as her model in writing it. I still chose to close my mind to such thoughts, and visualize it as so much much more unimaginably greater.
Back to Atlas Shrugged. Not all the reviews I have heard are good. On criticism, in particular that sticks out with me, has to do with the quantity of repetition in the book. Repetition in a book is quite tiring to me.
If my not reading the book leaves me disabled in understanding objectivism, then so be it. I'm not an objectivist anyway, at least not in any pure Randian sense of it. But I do however view Rand as the Greatest woman of the Twentieth Century, even if all her reported faults are true.
So be it...but let it be known that I don't read fiction either usually. I loved Fountainhead and love Atlas Shrugged. There are huge parts in Atlas Shrugged that are so insightful. They shouldn't be missed.
I think a much better written, shorter, more rousing, and philosophically comparable work that will put you near the pitcher's mound of what Objectivists are trying to say, I would suggest reading Robert Heinlein's The Moon Is a Harsh Mistress.