I used to give Dune to my teenage relatives and it usually turned them into avid readers; they would thank me later. I noticed that it doesn't hold the interests of the recent teenagers in the family; it is hard to get them to start and even harder to get them to finish. I think competition from the internet, youtube and cellphone is just too strong. That is horrible because developing a passion for reading helps lot in highschool/college/life. I've offered to pay them $100 and they still won't read it!
I read most of the Dune books back when I was a teenager, and despite being a usually voracious reader I found them very hard to get into. Worth the effort, mind you, but it's definitely a series which requires some investment.
This is very close to how I feel about Kim Stanley Robinson's Mars trilogy. I read them because many of my friends who were also sci-fi readers raved about them.
I enjoyed Red Mars but I really had to slog through Green Mars and Blue Mars. Red Mars was fun and interesting, but I could have done without a few hundred pages of Sax Russell talking about plants in Green Mars.
I think worldbuilding books take a certain level of investment, even among voracious readers.
