"A children's story which is enjoyed only by children is a bad children's story. The good ones last." --C.S. Lewis
It's said that if you've read a book before seeing its adaptation, you'll like the book more, right? That's how I feel about Avalon. A lot of this book is clearly inspired by Firefly. Problem is, I love Firefly, and it's not until maybe the last third of the novel that I started to notice the differences between this book and Joss Whedon's television show. The last third feels more like the book started to embrace its own world, reminding me a bit of Glow by Amy Kathleen Ryan mixed with homages to Star Wars and Firefly, and that was when I started to fully enjoy the novel.
The book isn't exactly like Firefly, of course. The author changes the character relationships, adds more of a YA background to develop the characters and their backstories (including an explanation for how a teenage band of mercenaries exists and succeeds). And Avalon is enjoyable, the character banter, the action, the epic scope of the world. It's well-written, if a bit slow in the beginning so that you've acclimated to the characters and their situation, and the romance is actually a sub-plot in the face of the adventure, conspiracy, and action. I have no doubt that this novel will reach quite a number of fans. I know that this is also pitched to Firefly fans, but I would suggest giving it to more reluctant science fiction or action-oriented readers first.