The series is a popular one, and kids will gravitate to the familiar character.  The rhyme helps build literacy skills.  The situation is one that many students can relate to:  little Llama is going on his first overnight sleepover at his grandparents’ house, but he leaves his treasured stuffed llama in the car, which leaves him feeling nervous.  When he finally confesses, grandpa comes to the rescue by sharing his own special toy from when he was young, emphasizing the point that we all were young once, we all get scared at times, and we all cling to our special somethings.  Literature snobs may cringe at the poor grammar, as the whole thing is written in sentence fragments, but as my high school English teacher told us, once you know the rules well enough to break them intentionally, you’re allowed.