The issue of the succession to Mohammad is one of the seminal events in the history of Islam. That the Umayyads - a clan who previously had actively opposed Mohammad and his teachings and who converted to Islam rather late - would lay claim (and be succesful in their pursuit of) the caliphate was tremendously controversial. In fact, this issue is at the core of the scism between the shi'a and sunni. Because of its importance (both politically and dogmatically), a balanced and nuanced history is difficult to find. Hawting, in a little under 150 pages, does this.
The political, social and economic climate of the 7th century is vividly depicted, and the personalities, inter-tribal rivalries and competing claims to the succession are concisely told. This is an outstanding history written by a seasoned historian. As a previous reviewer has noted, Madelung's history of the Umayyads is much more detailed, and is certainly recommended for those who are seeking a more definitive history of the period in English. For the rest of us, however, Hawting's treatment is the one I recommend.