I purchased three guides for a trip to the Sacred Valley and Machu Picchu - this turned out to be the least helpful of the three. First, despite being dated 2011, it was the most out of date (even compared to the Frommer's Peru guide dated 2010). I just never knew when this would crop up as a problem. For example, I asked about the "Machu Picchu Pueblo Hotel" in Aguas Calientes. Turns out no one calls it that anymore, it is the Inkaterra. (Frommer's and Fodor's got it right.) Second, It mysteriously over-reports some restaurants/lodging at the expense of other options. For instance, this guide spends 9 column inches blatantly selling the lodging and eatery at El Alberque in Ollyntaytambo (pp. 49-50). The next longest write-up for other lodging or dining options here is 2 column inches. Finally, the maps don't always seem to synch with the text. For instance, we are told the Museum of Religious Art in Cusco is at the corner of Palacio and Hatun Rumiyoc (page 95). But look at the map on page 91 and it appears to be at Palacio and Triunfo.
Overall, my impression is this book, compared to the other guides, was put together with less information and less quality control. That is, perhaps, why it is a little less expensive. But if I'm going all the way to Peru, I'd rather pay a few more dollars and know I'm getting it right.