With this 1st edition "Let's Go Peru" is getting off the proverbial porch and running with the big dogs (Rough Guide & Lonely Planet -- see my reviews). "Let's Go" is outstanding in two areas: Budget Travel and Alternatives to Tourism
Budget Travel. "Let's Go" guides are known for their ability to find you the best bargains. So, if you are counting every `centavo' then this guide will come through. The authors will find you a rock bottom, dirt cheep, bargain basement, lowest price possible accommodation and restaurant to match. IE: Hostal Rocha (gotta love that name) in Huacachina goes for $2 a night and you might bargain them down.
"Alternatives to Tourism." This twelve-page section covers "Volunteering," "Working" and "Studying" in Peru more throughly than any other guide. Each listing includes the names, address, phone numbers and electronic contact information that you will need. So even if you are not a minimalist, but you are planning to stay in Peru for a while, you will want to have this information.
I have lived in Peru for the past five years and I have frequented many restaurants listed in this guide. With the exception of one or two, "Let's Go" is right-on-the-money. I found the listing to be up-to-date and their descriptions are the best of any of the guides out today. For those who love "Nightlife" (bars & clubs), these sections are great. All of their recommendations are easy to find on a fairly decent map.
The Andes can be brutal if you get altitude sickness. I have seen the effects of "severe" altitude sickness, and it is not pretty. Sadly, for some Dilbert reason, `Let's Go Peru' only gives you the altitude of about 60% of the cities. They include the altitude of Tacna (562m or 1,842' ), but omit the altitude of such place as Puno/Lake Titicacawhich, which is at the nosebleed altitude of 3830m (or 12,565'). Go figure. Altitude information is important, and yet only `Lonely Planet' list the altitude of all the cities.
Some areas need additional work. The "Essential" section (Documents, Climate, Money Etc.) in this guide is bare-bone-basic and not as good as other guides. The four pages "Staying Healthy" section is anemic and barely covers important health information (in comparison, Lonely Plant's devotes ten pages about all important health information needed for your trip). Though the maps are easy to read, the guide has fewer maps than found in the other mentioned guides. These disparities will probably will be corrected in the 2nd edition.
Bottom line: This is guide is especially valuable if you are trying to do Peru on your lunch money and/or may stay awhile to work, volunteer or study. Caveat: if Machu Pichu, the Inca Trail, or the Manu National Park (Peru's Amazon) are your primary destinations, then you will get better information from either `Rough Guide' or `Lonely Planet'. Happy Trails. Strongly Recommended.