I ended up liking this quite a bit more than I expected going in, though it didn't completely win me over.
Let me admit this upfront: Beauty and the Beast is my absolute favorite Disney movie, and may be my favorite movie full stop. I don't mind weird twistings of the original story, but the Disney version itself is almost sacred to some extent, so messing things up was going to go very very badly with me.
This didn't really mess things up.
Now, I admit the Beast was a horrible person, but that's kind of part and parcel of the origin story of the movie. He's supposed to have been a huge spoiled brat who thinks quite a lot of himself, but it was hard to read sometimes. Yes, he starts out problematic in the movie, but not to the extent that he was before the curse had taken hold, so seeing him at his full "glory" as a bit of a womanizing bastard was kind of rough reading, especially from his point of view.
It was intriguing, however, to see how things were "before", and to see what precisely caused him to be cursed. Some liberties were taken, though they are certainly excusable given the framing of the film, and they add some interesting factors to what appears to be a series of Disney tie-ins. The idea of a shared Disney universe is a lot of fun, and I'm willing to make allowances in order to have that and to see more of it.
I was not expecting the prominence of certain characters, and the way that was handled was clever. It added a depth to certain scenes in the movie that weren't there without the idea of that backstory, as did the exact nature of the curse, which was darker even than the movie suggested but still managed to fit in perfectly with the plot of the film.
I'm definitely picking up the other book in the series, and I look forward to more. If the author can manage to give me something that adds depth to a film I adore, I am intrigued to see what can be done with those Disney movies that I don't hold the same regard for, and to explore this new extended universe and see how things work.