Here is a surprisingly good book, written by a psychiatrist who interviewed the Dalai Lama many times. The book is a combination of narrative by the author and extended quotes of the Dalai Lama's answers. And Cutler asks some good questions.
Sometimes the Dalai Lama's answers seem simple. Part of it is the language. English is obviously not his first language, so he uses almost nothing but ordinary, everyday English -- no jargon, no technical terms, no psychiatric lingo. And yet he obviously has a profound grasp of human nature. Another reason his answers sound simple is because they are rooted in practicality. He isn't trying to explain how things are, he's trying to describe what you can DO to become happier. Descriptions of actions are much simpler and more concrete than explanations.
I'm the author of the book, Self-Help Stuff That Works, and I found the psychiatrist's orientation and the Dalai Lama's practicality combined to make some excellent self-help. I've tried many of the Dalai Lama's suggestions and they really work. One of his suggestions is to think about the similarities between you and other people -- specifically that they want to be happy, just like you do, and they also suffer, just like you do. I know it sounds almost too basic, but when I've actually thought about that while talking to someone, I feel noticeably closer to the person, and that feeling of closeness is relaxing, soothing, calming, and very pleasant. That feeling of closeness increases my happiness.
The Art of Happiness is an excellent book and I recommend it highly.