The strengths of this book are those of the other AA Spiral Guides: it's small and light enough to carry around with you, and there are loads of photos which are useful in deciding what to see.
The street maps of the city are clear, however we had a real problem finding the sights mentioned in the text on the map as they are not grid referenced. The Spiral Guide was very good for finding things to do, but we were glad to have a second guide book (Lonely Planet's Rome Condensed) with which to look up their locations.
Also, some of the information given was seemingly inaccurate and sent us on a few wild goose chases; for example a "vegetarian" restaurant a little way from the Spanish Steps was anything but, and we wasted ages trekking to look for a gate whose keyhole would supposedly give us an amazing view...if we found the right one it was a definite waste of time!
That's not to say the book doesn't have some useful tips on what to see, and it hasn't stopped me buying more in the same series - it's just that we encountered several flaws with this particular edition.
We mainly used this book to search out the must sees, and tended to stumble around the rest of the city ourselves. I think really it was a case of Rome being so amazing that we just kept finding things to see without needing a guide book. For a general overview this book is excellent, however we found it impossible to find many of the places mentioned on the maps and this is a major issue.