Having not especially enjoyed Rand's The Fountainhead, I was surprised by how readable Atlas Shrugged actually is. Once you accept the ridiculous premises of the fantasy world Rand has constructed, the plot moves along at a fairly cracking pace as long as you ignore the political speeches (and there aren't in fact all that many of them, though one of them does go on for fifty pages).The evil guys are evil, the good guys are mysterious and threatened, and Dagny's moral dilemma is almost realistic.
It is of course an absurdly premised book. The dystopian society that Rand portrays is rather closer to We and Nineteen Eighty-Four than to anything the US is ever likely to develop into. Her heroes' response, to sabotage the economy and steal from their own companies, is itself pretty immoral. (At one stage she has a whole trainload of lefty do-gooders killed, but we are meant to understand that it's OK because they had it coming to them.) The fundamental axiom that you should never do anything for anyone else is impossible to comprehend for anyone who has ever contemplated having children (or even pets) and is in fact contradicted when the good guys rescue one of their number near the end. But on its own merits it holds together, and I think it's possible to admire the structure without sharing the sentiments.
Atlas Shrugged is certainly a work of sf; quite apart from the new metal developed by Hank Rearden, Galt is able to conceal his valley refuge by arcane means and, Vogon-like, to take over every radio in the country to broadcast his message, and there is the catastrophic explosion of Project X. So I think it qualifies as one of the important political sf novels that any fan with an interest in politics should consider reading; but I also hope that not too many people take it seriously.