...I was disappointed.
Revolution is just a novelization of the TV Series. That's it. And a rather kid-ified version. For some series that might work, but for a series as visual as Korra, the book didn't work. They would have had to put in a lot of description and details for Korra to successfully become a novel, but as this is a children's book, the description was dumbed down or felt abridged. It probably would have been wiser to go with a comic book.
Also, because I've already seen the TV series, I felt like I had no reason to read the novel. It's one thing when a book becomes a movie or TV show—things are bound to be changed or cut out, so it's worth reading the book for that—but when it's a movie or TV show being turned into a book... especially a kid's book... very rarely is anything added. So it just wasn't worth it. In a hundred pages, the only things added were thought bubbles for Korra, and those I'm pretty sure they had Korra mumble in the show itself, so not really original content.