I have lots of guidebooks - and lots of Lonely Planets, for that matter. But despite the fact that they say they are for "independent travellers", I keep finding ridiculous reviews on restaurants and hotels, to the point where I've stopped using them.
The History, Snapshot, and similar sections are great, but if you have a brain of your own - use it. Forget their restaurant and hotel recommendations, as I'm not even sure they visit the places. Sometimes they have history or comments on places that is worthwhile to read, though. All tourbooks may have these drawbacks, to be fair.
Finally, I think I'm going to stop buying Lonely Planet's, though. First, they always act like driving is so scary everywhere, when it's actually quite easy to anyone with a brain. They also forget to give worthwhile tips on getting a car, etc. I imagine that this is their way of "saving the Earth". To a person who does care about the Earth, but doesn't believe that being a dirty hippie is going to save anything, this - and all their other BS trying to coerce their opinions onto you as fact - gets really freakin' old. Yes, yes, I know, LP is founded by some hippie freak from AUS or something - whooptie doo. That doesn't mean I have to pay some jerk who's going to push his politics on me, whether I agree with them or not.