I read it in my late teens/early 20's and was planning to reread it when I'd forgotten enough of the plot that I could fully enjoy it again. Then, unfortunately, the movies came out! Maybe read it again anyway? Not sure.
I read it at age 11, again at age 28. The difference in personal experience was remarkable. The best parts of the story were very different between those ages.
Another option is to listen to the audio book read by Rob Inglis. He's absolutely amazing in his reading.