alice_90 says:
its a really good book. you read it when you were younger and its a book that sticks with you and you want to read it again when you are older.

meyv says:
it's one of those books that always makes you feel good

EternalCynic says:
Because it has two levels. People read the book when they are young (or have it read to them when they are young) and its just a fanciful story, with a lot of ridiculous and humorous things happening. Later if people choose to reread the book when they're older, they start seeing a lot of deeper philosophical meanings underneath the silliness they perceived when they were younger. You essentially need to over-analyze everything in order to get the full effect of the book.