Anyone using OpenSceneGraph?

After running the demos, I’m very interested in OSG. However, I can’t seem to find any tutorials or users’ guides. The “documentation” that is distributed with it now, quite frankly, sucks. There is supposedly a book in the works, but I want at least to learn the basics before I buy the book. I’d like to use OSG to make a simple 3d action game, but I don’t know if it’s suitable for this purpose. Can anyone offer any help?