There are many out there. It’s good to look at them all and see what you like.
I’ve had good luck with Let’s Go and Rough Guide, and have used Lonely Planet and Moon Guides.
I like Let’s Go’s layout, and while some find RG’s wordy descriptions tedious, I like the background info. I’ve had a couple problems with LP’s errors in the past but have used their little pocket editions and phrasebooks.
Some enjoy Rick Steves’ breezy humorous style but his guides will have mistakes: not just outdated info, but real mistakes.
The Eyewitness series have some nice glossy photos and background info but that’s about it.
All guidebooks are just that, guides, and if they are not updated, prices and other info might be wrong.
If your public library has a good travel section, you can check a few out and see what style fits you best.

I prefer Let’s Go, they cater to the budget traveler.  I buy them used on amazon, can usually find one that is only two years old for around $5.  Not a lot of the important stuff is going to change in that amount of time. 

My favorite is a rough guide.  The best thing to do is head to your local bookstore, and have a look at all the options, and pick your favorite.  

my personal fav is the for dummies.  They are really good, and easy to read!  with everythnig the others have, prices, which were very close to the ones i paued last year!  and there were directions and info, plus usful terms!  its good reading!

My vote is generally for Lonely Planet.  Just go to a local bookstore and see which you like best and go with that.  When you really start using it you’ll find out what you like and don’t like and will be able to better plan your next trip.

I like Lonely Planet for some things, but I don’t think they’re as up to date as Let’s Go.  I traveled Ukraine, Romania, Slovenia and Croatia in 2004.  I had a 2003 Let’s Go Eastern Europe and a 2004 Lonely Planet Eastern Europe.  The Let’s Go was much more up-to-date (even though a year older) about things like getting around, the state of the rail system, the state of tourist infrastructure.  BTW, I took the Lonely Planet intact and just clipped the appropriate pages from the Let’s Go to save weight and space.   

I recommend to my readers to pick up two books: Rick Steves’ Best of Europe and decide between Lonely Planet, Let’s Go, or Rough Guide for your second book.

I used Rick Steeves when I was in Scandinavia, and thought his guidance was awesome! I like how he definitely tells you what is worth seeing and what isn’t; really helps save time. And his “guided” walks are great! I’ve only glanced at a few other guidebooks, so i dunno whether this is ubiquitous or not, but it definitely helps you hit what you really SHOULDN’T miss, and steer clear of places you really don’t want to be (i.e. west of the train station in Copenhagen; since Rick tells you not to go there, I got curious… hahaha)

I like to read Rick Steves guidebooks as they’re very interesting and easy to read and have interesting extra tidbits of information.  However, they are definitely “one man’s opinion” and I don’t always agree ….

Yeah that’s true.. sometimes stuff he thinks is interesting… well… isn’t… hehehe
 
But mostly its good stuff

thank you

I agree that Rick is entertaining and engaging, but he’s made some mistakes, as has Lonely Planet.
The bottom line is that these are guidebooks, not how-to manuals.

Yeah I would never take any train schedules or anything at face value.