A brief, whimsical joy -- especially ideal as a 'gateway game' for getting younger children into interactive fiction. Mr. & Ms. Kyratzes (his writing, her illustrations) capture the playful, timeless sense of being a mundane-kid-in-fantasy-land, without ever talking down to the player/reader.
Admittedly, the point-and-click interface has its shortcomings -- for example, conversation topics give away crucial plot points, before they've been introduced organically. But i'm honestly willing to overlook such (potentially fundamental) design flaws, because it's outweighed by the detail-rich wonder of discovering the world-at-large. Even more impressive, most of the puzzles can be reasoned out quite sensibly, in spite of the patently surreal setting.
Needless to say, if you're fond of the narrative tradition that includes the Oz series, Labyrinth, and a sizable chunk of Neil Gaiman's work, then you probably ought to give The Book of Living Magic a solid playthrough.