Over the past fifteen years, Jack Zipes has edited, as well as written commentary for, a variety of collections of fairy tales. When Dreams Come True: Classical Fairy Tales and Their Tradition is a collection of eleven of these essays, written between 1983 and 1997 (with some updating for the present book).
It would be unfair to judge this book as an intrinsic whole. The original essays were not initially written to be published together. As a result, some, such as those on Oscar Wilde and Frank Stockton, are bare-bones, providing the basic biographic detail. Others, such as those on Hans Christian Andersen and L. Frank Baum, provide much more scholarly analysis and detail.
Occasionally, the results are amusing. In the excellent chapter on the Brothers Grimm, Zipes is somewhat disdainful of overly-analyzing the intents and psychological state of the authors of fairy tales - only to seemingly engage in similar analysis in the following chapter on Hans Christian Andersen. This would be a more serious criticism, if the analysis of Andersen was were not as well-written and perceptive as it is. Also, as the Andersen essay is the earliest published in this collection, it's possible that Zipes included his prior self in the somewhat mocking attitude towards over-analysis. (And if the reviewer doesn't stop the paragraph here, he's going to be guilty of the same thing.)
Overall, When Dreams Come True is an excellent resource. The essays on the Brothers Grimm, fairy tales in Victorian England, and L. Frank Baum stand out as strong, detailed, and insightful. While not the ultimate compendium, the 20-plus page bibliography is a handy reference source on its own. Zipes has a talent, woefully uncommon these days, of expressing strong opinions without letting those opinions get in the way of facts or fairness. When Dreams Come True should be in the private library of all with intellectual interest in fairy tales.