I had heard about Lua more than a year ago, being used in my organization for a product, and I had heard that this book - PiL2e as the definitive guide, but only now I have bought and read the book. The book covers the breadth and depths of Lua, is concise and well organized, but still I wont recommend it to those who don't have any experience in dynamic/high level languages. For beginners "Beginning Lua Programming" might be an easier read. (I am yet to put the C-APIs and embedding to use, ...