La Llorona is a famous Mexican legend, and is a worthy selection to be included in school libraries, and if your library already has other versions, this one would make a reasonable addition for offering different versions of the same story.  In particular, this one is useful in introducing students to reading script formats.  But if you are only going to have one version of the folktale in your library, I wouldn’t recommend this be the one, as the script version can be a bit confusing, with sometimes Older David speaking as narrator, as he tells the story as a memory, and sometimes Younger David speaking within the memory.  And it’s got a story within a story, which is another useful literary device for teaching, but in combination with everything else going on in this story, it just adds to the muddled feeling of the retelling.