This Guide offers a pretty extensive coverage of every location of the game and has a nice step-to-step walkthrough alongside with maps to help you find all the items but also get straight to the point if you only need to reach a particular place on your subsequent playthroughs.

The only thing the guide lacks is tips about combat and the combat system in general, while it offers a few useful tips it lacks of some kind of "strategy guide" about how fights should usually be handled and doesn't suggest strategies exept in boss battles.
The Score pieces are also misprinted, leading to confusion if you decide to check what piece you are supposed to play visually (the first tree pieces are identical, so you have to check the next two to find the one you are looking for and the last two are missing), though their locations are correct.

In substance, it's a nice guide to have with you so you won't miss all the items in the games, and the maps for the bonus dungeon are just priceless, clear and helpful.

I was questioning whether to buy this Guidebook after checking out the reviews on Amazon. I almost didn't buy and man would that have been a huge mistake. How people thought this guide wasn't helpful is beyond me. What was so helpful you ask? The maps most importantly (beleive me you would be lost for hours and hours without it), the rare items you need to pick up (as there really isn't any warping device and would physically have to go back), the leveling up guide (so you can see who you want to be level up first and who heals and who they will heal), and of course the achievement guide, etc etc. Definately worth every penny!

A guide to follow step by step the game without left without anything and explain the plot of the game, perfect!

Eternal Sonata Official Strategy Guide (Official Strategy Guides (Bradygames)) (Official Strategy Guides (Bradygames)) is a nice player's guide to have for the game if you need it, but can be a bit confusing with the incorporation of the encore information in each section of the walk-through. There are things that are not explained in the guide, too, which can make a few side quests a bit daunting, but overall a nice resource.