His content is not well presented, but that doesn't mean that telepathic horses and all the myriad Xanth talents and amoeba people etc. etc. are intrinsically uninteresting. (Please mind you are talking to the person who wrote more than 500,000 words of Twilight fanfiction without changing any established worldbuilding. Salvageability of ideas is so different from quality of packaging.)
I know, I'd read your fanfiction and I enjoyed it :-)
I think you and I just have different definitions of "content". As far as I can tell, you use the word to mean "interesting ideas that could be used as building blocks for a compelling narrative", whereas I use the word to mean "the finished narrative". I could agree that Piers Anthony has some interesting ideas, though not all of his ideas are interesting, IMO.
I bought my niece a Kindle that just arrived and I'm about to load it up with books to give it to her tomorrow for her birthday. I've decided to be a sneaky uncle and include good books that can teach better abilities to think or at least to consider science cool and interesting. She is currently in the 4th Grade with 5th coming after the Summer.
She reads basically at her own grade level so while I'm open to stuffing the Kindle with books to be read when she's ready, I'd like to focus on giving her books she can read now. Ender's Game will be on there most likely. Game of Thrones will not.
What books would you give a youngling? Her interests currently trend toward the young mystery section, Hardy Boys and the like, but in my experience she is very open to trying new books with particular interest in YA fantasy but not much interest in Sci Fi (if I'm doing any other optimizing this year, I'll try to change her opinion on Sci Fi).