So, if you really want to have a solid Tibetan Buddhism 102, written in an incredibly human style, and you think you can handle some of the more punk-rock aspects of Buddhism (like the vivid descriptions of the hell realms) then this is an amazing condensation of the most important, vital teachings of Tibetan Buddhism, presented in thier full profundity.
However, if you just want to understand a little more about how the wisdom of Tibetan Buddhism could apply to your problems and inner struggles, it's probably a much better bet to get a book by Pema Chodron.