Through besthike recommendations, people have bought hundreds of Lonely Planet guidebooks. They reinvented the genre, in my opinion. Never buy any other company without first comparing against LP.
Sadly, for the past 6-7 years I’ve started to notice problems.
LP author Thomas Kohnstamm has a new book coming out this week:
A Swashbuckling Tale of High Adventures, Questionable Ethics, and Professional Hedonism
THE Lonely Planet guidebook empire is reeling from claims by one of its authors that he plagiarised and made up large sections of his books and dealt drugs to make up for poor pay.
Thomas Kohnstamm also claims in a book that he accepted free travel, in contravention of the Melbourne-based company’s policy.
His revelations have rocked the travel publisher, which sells more than six million guides a year – guides that generations of tourists have come to rely on.
Mr Kohnstamm, whose book is titled Do Travel Writers Go To Hell? said yesterday that he had worked on more than a dozen books for Lonely Planet, including their titles on Brazil, Colombia, the Caribbean, South America, Venezuela and Chile.
In one case, he said he had not even visited the country he wrote about.
“They didn’t pay me enough to go Colombia,” he said.
“I wrote the book in San Francisco. I got the information from a chick I was dating – an intern in the Colombian consulate. …
More alarming for hikers is that LP does not seem to be updating any their excellent walking guides as frequently as in the past.
BBC recently purchased controlling interest in Lonely Planet. BBC has their own problems, however. I’m not sure LP can recover.
besthike.com 
I’ve often bought both the Lonely Planet and the Moon travel book and left the Lonely Planet book home.
The only time I brought a Lonely Planet book with me, it left me standing at the Laos border without a visa it said I didn’t need.
I much prefer the set up of the Moon travel books because you can find what you are interested in, in the index and then go to what town will have those things and when you get somewhere, there are not a bunch of tattooed, tye dyed, “look at me” travelers holding their Lonely Planet book.
Once a followed the directions I found in a Moon travel book to walk through the jungle to a “deserted beach where the monkeys come out to play at dusk.” When I got there, there was one Chinese man. He said, “How did you find this place? Even Malaysians don’t even know about this place”
http://www.moon.com/
I use to be a big fan of the Lonely Planet guides, but in recent years I’ve found myself gravitating more to the “Rough Guides” more. Seem to have more accurate, and useful info.
The problem for LP is if they only recommend a few places then they give them a massive amount of business, usually resulting in declining standards, but to actually look at a lot it will cost money. Did they really stay in all 70 places in Rome ( a recent trip of mine, where the recommendations were good) ? Probably not, so they are relying on others recommendations. This was the way from the start of Lonely Planet, but other sources were never well acknowledged.
For walking guides sales will be lower, so updates will be less frequent.