I used to read the Xanth series several years ago, back in high school. I was actually a little bit disappointed with Realty Check in that I was expecting more comedy...I remember lots of puns and funny business from the Xanth series, this book really didn't have much of that.
I was also not so easily convinced that the characters would figure out the puzzles so easily! The character development seemed mildly weak, they just weren't beleivable at times. Lloyd, the 13 year old is introduced as an obnoxious little punk, but within a matter of minutes it seems he grew into a wise adult. Llynn was a bit too stereotypical, even admitting that she looks for 'bad boys'. The type of girl that likes a bad boy usually doesn't know or admit that they do.
Also the book had an almost creepy sexual tension at times, as there was plenty of sexual tension not only between cousins, but also between adults and minors. A few times it just left me wondering "huh?!" There was even a bit of sexual tension between 15 year old Llynn and Grandpa!
While I felt some areas of the book left much to be desired, it was really the imaginative and mysterious qualities I was looking forward to, and it came through big time there. I've recently been on a kick looking for stories that deal with time travel, dreams, and other fantasy related subjects. The simple idea that a house has doors that can open to any city in the world is a fascinating concept, and it's those ideas that I enjoyed most about this book. I don't want to give too much away that you can't read on the back of the book, but Piers Anthony is a very creative dude with a wild imagination, so if you're a bit of a dreamer you may well enjoy the book even if you agree with my above criticisms.