I've read quite a few books on mobile Java but this is the first I've seen for JSR-184. Most books spend far too long covering the basics (how to install Sun's WTK, etc., etc.) but Claus Höfele gets straight to the point. His descriptions and examples of how the API works have been most helpful - something the official documentation could do with. I'd certainly recommend this book to anyone wanting to have a firm understanding of mobile 3D.