We have the bumble bee and penguin backpack.  Both are sturdy and cute. We use one of them as a diaper bag for my baby. There is enough room for a change of clothes, diapers, wipes, spare bottles, and snacks. My three year old takes his to school with him.  It fits a change of clothes and his blanket for nap time.  He is able to wear the backpack without it hitting the back of his legs like a regular size backpack would do.  I've had them for a year now and with daily use, they have held up perfectly.