This book was a disapointment. It is done by a very professional historian, and so it cannot get 2-stars - but it should have been much, much better.
First of all, it is not a chronological account, but is topical (with a heavy emphasis on minute descriptions of various aspects of what would be called 'social history'). Worse - apart from being dry and not very well organzied -- the author is apparently bored with the main lines of his subject and more interested in the unimportant byways. So, in his introductory chapter - the overview chapter - Magellan and de Gama both get a sentence, but pages are devoted to the Portugese exploration of Ethiopia.
Boxer's The Portugese Seaborne Empire is likely better, but prohibitively expensive.
For a basic account, it's best therefore to look for Boxer, Diffie/Winius (also not cheaply available: http://www.amazon.com/Foundations-Portuguese-Empire-1415-1580-Expansion/dp/0816608504/ref=sr_1_1?s=books&ie=UTF8&qid=1323109948&sr=1-1), or to stick with Parry - which I'm now going to reread.