Blue Emperor is a book that I'd actually passed up the chance to buy for a relatively low price on a few occasions, due to their all occurring at times when I didn't consider such a purchase to be financially prudent. I definitely wanted to read it, though, and it was just recently that I was able to do so. The book was actually one of the earliest Oz pastiches. Well, they called it a pastiche, and I guess in some ways it was (Blossom did seem to stick to imitating the style of the traditional Oz writers more than some other modern authors have), but I think the more appropriate term is the more modern "fan-fiction." It was written with the typical fannish desire to tie up loose ends and contradictions in the canon, in this case primarily the identity of the Blue Emperor who had given Kabumpo to King Pompus. Ruth Plumly Thompson had originally said that the Elegant Elephant was a gift from a "friendly stranger," but in subsequent references had referred to the Emperor as the elephant-giver. Blossom tied in these references to ones to another mysterious figure from the past, Ozma's grandfather. All in all, I think Blossom did a good job, but there were a few oddities. Chapter 2 has Pompus not remembering he has a brother, even though Kettywig, his canonically established brother, is mentioned right at the beginning of the chapter. The Gump initially refers to the title character as "the ruler of Seebania and the Blue Forest of Oz," but almost all subsequent references identify him as the former ruler of all Oz. There are even some mentions of his being the FIRST ruler of Oz, which would seem to contradict Ozma's statement in Dorothy and the Wizard that the land had been ruled by a succession of kings and queens named Oz and Ozma. Even more confusing is that the bibliography also implies that the Emperor might be the same as the old King of the Munchkins mentioned in Giant Horse. Was he a local ruler who was eventually elevated to reign over the entire country? It's not really clear.
As far as the actual story and writing go, I'd heard of people not really liking it, but I thought it was good. Blossom reused some old locations (like the Fiddlestick Forest) and introduced new ones that really fit in with those in the Famous Forty. Electracity was characterized by the same sort of humor that Baum had used in Utensia. The established characters (particularly Kabumpo, who's always been a favorite of mine) stay true to form. While the Emperor himself makes only a brief appearance, other characters' memories of him establish him as a character who fits quite well into the Ozian cast. On the other hand, I think most of Blossom's totally original characters are somewhat weak. I didn't get much of a sense of personality from Muab or Gussun. And Mossolb was pretty much just a stock evil Ozian magician character, all frantic ranting and absurd threats. And as those names indicate, Blossom was one of the first Oz authors to utilize a cheap, easy way to come up with new names--just spell other people's names backwards. Chris Dulabone would later overuse that technique in The Deadly Desert Around Oz. It isn't TOO bad in Blue Emperor, although it's sometimes hard to remember which Gump is Muab and which is Namyl.
There's certainly more I'd like to say about the book, but since I doubt anyone even read this far, I might as well quit while I'm ahead (just like Namyl the Gump should have done).