I'm not sure what the issue is with DOAWK for a younger kid. Our DD8 just took the SB5, and one of the results that had us curious was her lexile level. So we plugged that into a search, and were immediately provided three recommendations. Two of them were Harry Potter and Diary of a Wimpy Kid, which caused DW and I a good laugh, because those are the things DD's reading most these days. It looks like that test nailed her.
The third book was The Hobbit, which I did in 9th grade AP English a quarter century ago.
Now, if she was still reading DOAWK in 9th grade, I might be concerned.
Personally, I don't care what kids are reading for pleasure, as long as they're reading. The only problem I have with this topic is what they're reading in school. Reading, dissecting, and discussing important literature is one of the most effective means for teaching critical thinking skills... a skill set that is disappearing from our society.
