Two things you should know before reading Beauty:
1 - Beauty was written in 1978, about 15 years before Disney's Beauty and the Beast came out.
2 - This is Robin McKinley's very first book.
Now, the first point is key, as there are a number of details with which the book seems to overlap with the Disney film. In fact, as I was reading McKinley's book, I couldn't help but wonder if the Disney epic had been based on her novel. Since I adored the film, I had absolutely no problem reading a similar (yet very, very different) version of the Disney tale. Still, it is important to remember that any Beauty/Disney overlaps are not at all the fault of McKinley.
In regards to the second point, I found it rather reassuring to know this was not the pinnacle of McKinley's achievements. Although I enjoyed Beauty, it was not a breath-taking literary achievement. Having heard so many great things about McKinley's writings, it was good to know that she's had 30-odd years since the publication of Beauty to refine her style.
Now on to the good bits. Although I have no knowledge of the first Beauty and the Beast tale, McKinley's style made me feel like I was reading the original version of the story. It was almost as though I were reading the un-filtered first version of the tale - without the weight of an author behind it, visibly guiding the story. Instead, this book just... was. You know what I mean, right? When you read Beauty, you can't even begin to imagine someone actually writing it. The book, surely, just came into existence by itself.
And, because of that, I feel rather odd describing my issues with the plot - or rather the lack thereof. Even though, yes, this is Beauty and the Beast, everything still felt rather mundane. Beauty does this, then that, then the other, and then things work out to be such-and-such. It was more of a historical account than a dramatic novel, with none of the twists and curves you'd expect in "real" book.
But still, I really did enjoy Beauty. My unwavering love of the tale probably made me more forgiving of its dull moments... yet, I've no doubt that McKinley is a skilled author worth of praise.
Bottom line? Beauty is a must if you are a fan of the Beauty and the Beast tale. But if you're not, I'd try something else from McKinley's repertoire.