I bought it, but Serebii pretty much posted all of its contents already, plus other info that wasn't in the guidebook (like Pokémon stats/movesets, other Mega Stone locations, etc.).
What Serebii DIDN'T post were hidden item locations, but they're not that important (unless you have OCD like me and NEED to get EVERY SINGLE ITEM!).
EDIT: Fighting SIX Lv 65 Audino at Battle Chateau
(Black Writ of Challenge only; obtainable after you beat the Champion then rank up to the last title) + EXP Power Lv 3 + Lucky Egg + Max Affection = 19,550 EXP EACH = 117,300 EXP!... I can only imagine how much that'd be if I was raising another Trainer's Pokémon
EDIT 2: After fishing for like 2 hours, I FINALLY got a Dragonair ._. These fishing rates, ahhhhhhhhhhhhhhhhh!