I like the book. I lose respect for anyone who just dismisses it out of hand because they think that's the cool choice.
But I agree that the plot and characters are shallow. The book was designed to showcase her philosophy and it does it well. I don't believe it was ever intended to be realistic, and I think it fell a little short of being entertaining a lot of the time. It was far too long. It was still far better than a lot of other fiction books I've read.
What I get out of the book (which I've read 3 times) is a different look on self-worth and self-sacrifice than all the rest of society gives. I believe people would be better off if everyone acted in a rational manner to promote their own interests. (It's not actually rational to hurt others to promote yourself. In the long run, that's a losing strategy.) I also believe that this will never actually happen, and so compromises are in order.
I believe that book has helped me form a better sense of my own worth, and was at least partially responsible for me leaving a job and getting a 40% raise at the next one. It's not the only factor, but it helped to be able to objectively assess my value to the company, as well as how much I value my own time.
Does that mean I'm a card-carrying Objectivist who doesn't give to charity? No. It means I'm a more rational person who evaluates things a little more clearly. In fact, I actually give to charity more now than before, so the book can hardly be said to have hurt that. I do give for slightly different reasons now, though. Before, I gave because it was the thing to do. Now, I give because I want that charity to work. If I give to the Red Cross, it's because I want them to help sick or hurt people. If I give to Child's Play, it's because I want sick children to find a little bit of joy in their lives. Those things may seem obvious, but they weren't.
A good example is United Way. I don't give to them. Why? Because all they do is slice off a large percent (13% apparently) and give the rest to an actual charity. Before, I had never really considered this, and just bought into their propaganda.
"Of each dollar United Way collects, over 87 cents goes directly to valuable community services. " - http://www.forsythunitedway.org/faq.cfm
They used to be very vocal about how much went to a real charity, pushing that statistic in front of you like it was a good thing. That is not good. That 13% could be going to a real charity, too, and actually helping people.
So in the end, don't lose respect for people merely because they like something. You might not be seeing the whole story.