All 3 of my boys love this series. My youngest son is now 2 and they are well-loved ie, covered in clear packaging tape, but will stay in the 'keep' pile for grandkids someday! Even though I have had to repair them, they are sturdy little books--the 'lift the flap' is a very sturdy cardboard. I'd even go as far to say that they are THE sturdiest 'lift the flap' books that we own. After 3 boys, we own A LOT of books, but we come back to these over and over. It's one of my favorite books to give as a gift, too.