Works pretty well, but not having a lock file and accidentally relying on packages that are in the node_modules folder, but are not present in the package.json, causes some occasional breakages here and there.
Does what it's supposed to do. I can't think of any issues with it.
Fits the state model of livesplit-core really nicely and is a really good fit for LiveSplit One for that reason. The performance isn't all too great though. But that's really only a problem due to the 30 FPS refresh rate. For any normal web page React should be just fine.