I had one for X and XII. The one for XII I think was highly needed, well not entirely because in this day and age you have GameFAQs which is free, but I do like the convenience of not having to go into the other room to look something up when I have a guide in the room with me. For XII you would miss a lot of stuff without the guide. You might not know until it's too late that you missed a great item from a random treasure chest and you would never know about getting the Zodiac Spear without it. I never bothered to get it myself as I found it boring and taking out the fun like the Excalibur II quest, but if you're a completionist the guide would help you greatly in regards to quests in XII.