While there is the obvious message that in forming true friendships it is what is inside that counts, I think most kids will skip over that and just think it's hilarious that a human and a dragon are exchanging letters and focus on the wacky misunderstandings that result from this fact. I found this book pleasant enough, the rhymes are particularly enjoyable - but my 4 year old (who is a bit young to grasp everything that happens) asked to read this book over and over.
BUY HERE (or request at your local library!)