This is an excellent overview of the Evolution-Creationism debate, authoritative and yet quite readable. While there is no doubt that the author firmly supports Evolution, she strives to present both sides of each major point in the arguments. The reader will gain an excellent grasp of what Evolution is about, the scientific evidence that supports it, the major counter-arguments made by creationists, and why those are scientifically unsupportable.
I recommend the latest edition, the second, published in 2008, but any edition is well worth reading. A preview of the first edition can be found on Google Books. It's available in paperback and hardcover, and can be found in many libraries. The ISBN of the hardbound, second edition is: 9780313344275, published by ABC-CLIO Inc.