This guide book has a small amount of information about a large number of topics. It comes with a pull out map. Both map and guide are well made and durable, although we needed reading glasses. It proved adequate for a short break to Rome; more info on a smaller number of topics would have been better for us.
The main drawback is that it is not a *practical* guide. For example, it does not compare bus and train journeys from the airport (hot/long vs short/more expensive); it suggests to "pop into" St Peter's - not mentioning the queuues that make that impossible (best before 8:30am); there are at least three ways to avoid the *huge* queues at the Colosseum, but it suggests none of them (best book in advance online at the official website).
The book is too large/heavy for a pocket, but that's probably true of most guides.
The map, while durable, is not entirely accurate; North is not as it seems to be indicated; exits from eg Piazza Navonna are not exactly as shown; the orientation of Trajan's Arch is incorrect; and so on. You can get by with it, but if you are good with maps, expect some frustration.