If you're interested in learning about the history of the Protestant Reformation and the impact it has had on the world, this is not the first book I would recommend. Hillerbrand's book is, however, probably the 2nd book I would recommend. Start with a broader, more comprehensive history that ties everything together, then read this book for the actual writings by the people who shaped the Reformation. Hillerbrand writes an excellent introduction, and a chronology/timeline lists the major events, but the real strength of the book is in presenting the actual writings by the movers and shakers of the Reformation.
My favorite part was the chapter on Martin Luther. Luther wrote for the common man, and his words are amazingly clear and concise. The theological issues that Luther wrote about are as relevant today as they were five centuries ago when Luther lived.
One fascinating chapter contained parts of William Tyndale's New Testament, published about 80 years before the King James Bible. It's amazing how much the English language changed in those years. The Tyndale Bible is very difficult to read, while the KJ version is close to modern English.
These writings make the Reformers come alive as real people. Fascinating reading.