One usually supposes that a guide is for visitors or foreigners. I have been living in Italy for the past thirty years or so and I think I can say that of the very many times I have been to Rome (or anywhere else in this country for that matter)I have never gone without taking the appropriate Blue Guide along. Like other Blue Guides the present volume tends to weigh a ton but no other guide to Rome can compare with the high level of its historical and artistic comments. Also much appreciated by English-speaking locals and of course by "double culture" creatures like myself.
The first time I was in Rome by myself, I took this guidebook and the DK Eyewitness guide and the lonely planet guide. I found myself using this one 90% of the time, and the other two 10% of the time.
When you're looking through it before buying it, it looks thin on photos and other pretty things, but when you're there, the information is brilliant. What it lacks in looking pretty, it more than makes up for in accurate historical and cultural information.
It takes you by the hand and walks you through every detail of every major monument in the Eternal City. The maps at the back are quite detailed, but like all guidebooks, use the internet to find hotels and/or restaurants; so ignore that info. (No guidebook will be up-to-date regarding hotel and restaurant prices etc - prices are changed quicker than a new edition of any book can be printed.)
If you're going to Rome to experience its magnificent art, architecture, history and culture, this is the only guide you will need. If you're going to Rome to party till dawn, you probably wont understand any word or concept printed in this book.