for what its worth i use the Lonely Planet guidebooks as I find them easier to navigate....
i don't 100% trust everything i read though as throughout my travels i have unearthed a few untruths, anomalies and a fair amount of 'flowery description' haha. that said, i am aware of how quickly places can change and know its not easy to stay on top of everything that takes place in a destination. LP cover everywhere I can think of every travelling to and yep, you can buy them everywhere.
LP have served me proud on a number of trips now and just yesterday i bought the LP india to take with me on my next trip.
definitely look out for the photocopied guidebooks in se asia... bargain! also you can always swap them at hostels/guesthouses etc
when you get to se asia they will have tons of cheap knock off copies of LP guides - they are a fraction of the price of new, legit ones. beware though that the quality is sketchy as you may find a critical page or two missing...
Oh please don't support these criminals!
Never forget that a guide is written by a human being.
The question is : do you have the same profile as the guide's writer ?
A good example is LP 2004 being really bad for North Mexico, sometimes even advising hoteles which run mainly based on prostitution and alcohool.
But the LP 2006 for North Mexico erased these bad hotels and is very good.
So the point is not about choosing between LP or Footprint or whoever, but between LP 2006 or Footprint 2005, etc...
I much prefer Footprint, since their transport information is far better. That said, LP has the better city maps, so it all depends on what you need in a guidebook.
Ive always been a fan of the Rough Guide and have quite a few ones for indivdiual countries.
I do think that they lose something in the compound editions like ROugh Guide to South America. I brought that along with me but soon realised that it wasnt great and I ended up givuing it away and managed to pick up some individual RG's or LP's again. I also had the Footprint Patagonia but found it a bit wordy.
I really just find guide books handy for when you are arriving somewhere - getting your bearings, transport options, etc.
Accommodation recommendations from the guides tend to be a let down I have found. (I think once a place has a listing in one of thse guides, they let their standards slip or something - just my opinion)Best accommodation I have stayed in are usualles ones I have stumbled across or had recommended by other travellers.
The guidebooks are so weighty as well I really just wanted to chuck mine out but they are really necessary for those first few hours in a new place. Bringing more than one is a serious pain in the ass