I'm sorry but the above reviewer downplaying the situation in Juárez is dangerously uninformed. Yes, people cross the border safely every day, but that doesn't mean that it is wise to do so. I grew up in El Paso, across the border from Juárez. I've lived in Mexico since '99 and regularly traveled up to Juárez on business. I still regularly travel through out much of Mexico on business. However, I no longer go into Juárez. I personally know too many completely innocent people in Juárez who have been gravely affected, and even killed, due to the violence.
A big difference between the U.S. and Mexico is that in the U.S. we tend to exaggerate the news. In Mexico they down play it because of the threats reporters face. I have also personally witnessed occasions where gun battles took place which involved automatic weapons and grenades, only to see it either completely ignored by the press or extremely downplayed. I'm not the only one who has experienced such things.
Sure, you can enter a place once and very possibly have nothing happen... ignorance can be bliss. But the more you go somewhere, the greater likelihood you will have of finding yourself in a very undesirable situation.
If someone is really actually laughing at the supposed exaggerated violence, they are uninformed. Try googling "blog del narco" or "diario del narco". These are underground websites run by Mexican reporters who are actually trying to report what's going on. (And even they don't report everything.) The U.S. is unaware of probably 95% of the daily violence currently affecting this country.
All that said, there are still many areas in Mexico where you can travel and visit in relative safety. Mexico is an extremely large country and there are still numerous regions which have not been greatly affected by the drug war. Guanajuato, Puebla, Yucatan... Great places. However, the states of Chihuahua and Tamaulipas are far from safe. Personally, I think the best places Mexico has to offer are in the middle of the country.
As far as this book... Lonely Planet continues to be my book of choice for Mexico travel. They're definitely the standard bearer when it comes to Mexican guide books.