I read Atlas Shrugged as a 15 year old, and again as a 29 year old. I think it's better suited for my 15 year old self, as I found the historical context of the book more interesting than the philosophy this time around. It also just goes on and on and on -- you get the general premise early on and it feels overly verbose by a factor of 2-3x. The characters don't age well either, my older self has found them to be kind of flat and boring.

Still, it's a good read. Especially the economic mechanics of the universe -- it's fascinating to read about the technology, culture, sexism, and politics from the first half of the 20th century. That alone makes it worthwhile. For example, the characters are constantly smoking cigarettes, to the point where pivotal moments in the plot are revealed, more often than not, because of a smoke break.

I second Atlas Shrugged. It resonates best when you are in your teens. As you grow older, you see the fallacies in it. But these don't surface much when you are young and it acts as a good motivator for the entrepreneurial mind to go out there and work hard.