Being a Michelin guide this book is packed with detail, well researched and reliable - despite Trattoria Cescarina in Santa Margherita Ligure having been unfairly dropped from its recommendations - BUT buyer beware: apart from a small explanatory section in English this is all in Italian. Once you've got the hang of the symbols and sections it's still possible to work out which places would be worth visiting, but if you don't speak Italian you miss out on the reviews themselves.
I have used Michelin red guides for about 40 years; while updated the reliability remains consistently very high. You may find good restaurants not in the book but rarely will you find one in the book that is not very good.
First it is completely in Italian, I do know that it is mentioned, but they could translate it in English! I bought the one for France who is in French too, but as I understand French I kept it. I find it very difficult to find what you need! It is very small writing and not very clear! I haven't used mine at all. I have got to say that with the Internet, you can go on Michelin website for free anyway. If you go on an unplanned holiday and you need a book to help you, I still wouldn't go for this one. It is not reader friendly I am afraid!