The book does what the title says: It presented me with a largish number of socialist fairy tales (late 19th/early 20th century), a genre I didn't know existed - looking back, it makes perfect sense, though. - I can't say how comprehensive this overview is. The stories were all a bit similar and mostly not very good. I don't want to hold this against the book, so I'm unsure how to rate the book.
I know little about socialism and I actually learned some theory from the book; still, I would have preferred fewer stories and more about the authors, the audience, how these works were received and what influence they had. There is a foreword addressing just these points, true, and I guess I could always go to a history of socialism in the UK to find out more.