I have enjoyed past efforts by John Julius Norwich particularly his 3 part history of Byzantium, which is a must read for anyone who seeks to understand that particular topic. Mr Norwich has a profound knowledge of medieval history particularly of states and countries bordering the Meditteranean (another one his books).
Sadly this book failed to meet this higher standard. Mr Norwich attempts to compress the history of the papacy into one book, it means in practice that he dispenses a number of popes in one or two paragraphs – it detracted from the book, the minimal treatment just gave a laundry list feel to the book.

The constraints of space meant that he couldnt truly cover themes or recurring issues in the papacy. There are better options out there if you are looking for a history of the papacy.