If you are looking for an entertaining, understandable, and well-informed introduction to the Reformation, I'd encourage you to pick up Steve Nichols's latest book, The Reformation: How a Monk and a Mallet Changed the World. Steve is a great historian and a great communicator.
The Contents and Introduction and Chapter 1 are both online. You can also check out the book's webpage that contains a number of helpful links, art, and other other supplemental material.
