Atlas Shrugged is pretty dreadful solely as a work of art. There are elements of the story that work and more than one intriguing mystery, but the execution as poor. The characters are very flat. Her heroes never do anything wrong, and her villains are nothing but straw men. There is very little urgency in the book; partially due to storytelling choices, partially due to the over-use of passive voice. When two characters meet in the book, we are immediately treated to 200 pages of their backstory from the time they first met until the present. This can be either trimmed or dropped in when part of the characters' relationship needs to be clarified or emphasized.
There is also a large amount of summary instead of scene, so Rand ends up telling us what her characters think instead of showing us. The one time where she errs in the opposite direction is Galt's 400 page speech near the end of the book. It was extremely repetitive and derailed the story for a long time. In fact, after the speech, I dropped my rating of the book to 1-star until the very last chapter.
The story itself is overall depressing. Rand seems to say that it's no use in fighting The Looters; smart people should just let the world collapse and build a new one out of the chaos.
Rand does have something to say about the over-reliance on others to make decisions for us and the need of many people to play it safe instead of striving to make things better. I just don't think she had the talent to do it herself.
And because I can, here is Whittaker Chambers's epic takedown of Atlas Shrugged in National Review.