This book is lengthy yes, but if you really want a sincere and scholarly analysis of Islam from an objective perspective (a prominent christian theologian) then this is one of the rare books that will give you an accurate understanding of the subject. The visual aids in this book (i.e. charts, graphs, timelines)also make it very "user-friendly."
It is difficult nowadays to get an objective, nuanced opinion on Islam, neither flattering nor biased against it. If I were to recommend a way to try and achieve this, I would suggest reading several good books on the matter, including this one among them.
I was surprised that no one else had made a comment before to this masterful work, which, in my opinion, is impartial and wise and the best book on Islam one may find. It can be savored by the professional historian and the educated layperson alike. So I add mine, my rate being between 5 (content) and 4 (pleasure, sometimes falling to 3, sometimes raising to 5). I highly recommend it.
Other books that I would recommend reading (as Khaled M. Abou El Fadl -scholar trained in both Islamic and Western law- says, non-muslims "first and foremost [are to] learn and understand, because nothing helps the puritans' cause as much as Western ignorance, prejudice and hate") would be the following: A) ASSESSMENTS OF ISLAM: 1) Moderate Islam at its best: "The Great Theft : Wrestling Islam from the Extremists" by Khaled M. Abou El Fadl; 2) Harsh but well argued: "Muslims in the West: Redefining the Separation of Church & State" by Sami Awad Aldeeb Abu-Sahlieh; and 3) Autobiography of a courageous woman: "Infidel" by Ayaan Hirsi Ali. She is a controversial thinker with a very interesting life. B) HISTORY: 4) General: "The Venture of Islam", by Marshall G. S. Hodgson (nowadays a classic included in any bibliography on Islam); 5) Turks: "The Turks in World History" by Carter Vaughn Findley; 6) Political theory: "God's Rule : Government and Islam" by Patricia Crone; and 7) Jihad: "Understanding Jihad" by David Cook (it also seems interesting although I have not read it yet: "Jihad in Islamic History: Doctrines and Practice" by Michael Bonner).
Additionally, as a complement to "Islam. History, present, future", I would also suggest to read (hoping that will be of use for those looking for a broad framework to understand the past) the following works, whose scope is as amazingly global as K?ng's: 1. Agrarian cultures: "Pre-industrial societies" by Patricia Crone; 2. Economy: "The world economy. A millennial perspective" (2001) plus "The world economy: Historical Statistics" (2003) by Angus Maddison (a combined edition of these two volumes is to appear on December 2007); 3. Government: "The History of Government" by S.E. Finer; 4. Ideas: "Ideas, a History from Fire to Freud", by Peter Watson; 5. Religion: "The Phenomenon of Religion: A Thematic Approach" by Moojan Momen; and 6. War: "War on Human Civilization" by Azar Gat.