You don't need a guide book for Disney World either. But I found having the unofficial guide to Disney was well worth the cost in the time and money saved based on their advice. I know people who went to Europe without a guidebook, too. Personally, for $16 and a few ounces I would rather have someone list for me my eating, sleeping and water gathering options along with giving me clear advice on how to navigate the tricky sections where "follow the white blazes" might not be enough.