The subject is of course controversial, which makes it popular. So good for you, finding a way to make an easy buck.
The story is really quite expected though, isn't it? Every cliche and stereotype is mined ineffectively to produce the absolute highest form of pedestrian papal pedagogy possible through prose. I must give this book exceptionally high marks for managing to at once assert the Pope was homosexual and not in the least like an Elton John impersonator. Wait, no, he was a lot like an Elton John impersonator, except for the talent, and looks, and being a decent human being sort of thing. So the Pope (Leo X), who is more interested in romping with unsuspecting virgin kitchen boys and dressing in some sort of girded loincloth with gold flecks, than ruling, doesn't actually bother to cover up properly the most dangerous secret ever kept by the Catholic Church. (And did we point out he is fat? He is you know, fat. He's fat and balding and has purple splotches on his cheeks. Also dimples mean something. I'm not sure what because I'm not Italian or Catholic. Probably if I was Catholic, I'd get that dimple thing for sure.) He casually leaves the dastardly deed, and the planning of same, to a secretary, who is of course, neither homosexual nor well coiffed. Everyone knows truly pious people are never well coiffed.
Anyway, the plot procedes from there in a pretty predictable path to the present day. I won't give any spoilers, not that it would matter as most of the surprises aren't and the secret is broadcast from the first chapter.
It still might be a redeemable story if only the author had gotten a skilled English ghost writer to do the translation. I am pretending the horribly stilted at times, and at times overly casual, language of the book is a result of translation from its original Italian. I would hate to think the Italian people could have been duped by an amateur attempt such as this one in their native tongue. So that must be it. From the point the true believer appeared, suffocating and struggling for life, buried alive, the story took off. Shame the prose held it back.
I wasn't expecting much, and wasn't disappointed.
On the upside, it is very easy to read, inexpensive, and annoys the religious extremists. So points for that. It does have a good basic story, even if it has been done before. This is not The Da Vinci Code but it offers more cheap thrills and is a quicker read. There are also no formatting difficulties and the spelling and such are creditworthy.