My daughter (age 8) absolutely loves these books. We purchased the set of volumes 1-6 for a Christmas gift, and she had the first three books read before New Year! I had an opportunity to read to her one night when she wasn't feeling well, and I liked the message that was portrayed, which was based on the Biblical principle of not lying.
I bought the 1-6 set for my seven year old for Christmas and she didn't want to read them. She does not like trying new things. Finally, I made her read one. Now she doesn't want to put the books down. She's read two already.