I would highly recommend this book.It is well written and gives a vivid insight into the way Verdi approached his work,especially in his choice of plot.It also shows the struggle he had over the censorship of his work and his refusal to compromise with inferior libretti and historical themes.It is very readable.
That I've had this book for 25 years and that it is one of the most well-thumbed books in my library should be sufficient to say this book is an essential guide to Verdi's life and work. I like the format of Osborne's opera books (see also his Wagner, Puccini, Mozart and Strauss volumes) whereby the chapters correspond to each opera, with none skipped, and yet contain a rich biography of the great man's life.
The writing is somewhat partisan, with some occasional digs at Puccini and Wagner, but that partisanship often translates into genuine enthusiasm for the subject, and makes for a continuously engaging read.
If you are a Verdi fan, particularly if you are newly discovering his works, you will certainly love this book.