The post adventure strategy guide is only as expansive as the content found in-game after beating it. As such, I'll just list a few things not mentioned in the description to help other potential customers decide if it's worth buying this guide.
The poster included is approximately 30in by 37in, or 58cm by 94cm
The guide explains the functions of Battle Maison
The guide lists all available Pokémon found in Friend Safari
The guide provides the areas where the roaming legendary birds can be found to force them into Sea Spirit's Den
The guide provides ranking information for the Battle Institute
The guide provides extensive information for the Looker sidequest.
The guide has outdated information on the breeding mechanics. (to be discussed below)
The guide provides the locations of the megastones
The guide explains how the Pokéradar works
This strategy guide has the same layout as the previous guide, with an introduction of the new location with a checklist of items and Pokémon obtainable in said area, followed by points of interests worth checking out. Just like the guide before it, it has a list of the egg groups readily available, so there's no need to refer to the previous guide for the information. The guide also gives information on how Pokémon breeding works but it's a tad outdated. The information that is outdated is still correct, but it does not explain that the mechanics have been simplified, making it far easier to breed a Pokémon with the desired traits.
The first half of the guide does its job in assisting the player find all the post-game content while providing tips where applicable.
The second half of the guide, which is the Pokédex, is as informative as it can be. The Pokédex provides an in-depth look at the Pokémon's level-up moves, TM&HM moves, egg moves, and tutor moves. It also provides information on where to find the Pokémon, the facilities you can use them in, and the damage taken in both regular battles and inverse battles. Superfluous information includes their evolution line and front/side/rear views of the Pokémon. The Pokédex guide also provides extensive information on alternate forms, such as the multiple patterns of Vivillon.
All in all, the guide provides the necessary information that you need in one handy location if you dislike browsing the internet for the information and does a great job with the Pokédex. However, it does have its downsides:
The guide only has the Pokédex information for the three Kalos regions. So you won't find information on Pokémon not native to Kalos, like Rattata and Entei.
The information to find items is not as extensive as guides found online.
The Pokédex does not use numerical values for the base stats and still use the bar system from previous guides.
In Generation V, only the males can pass down moves, and only the females can pass down the Hidden Ability.
In Generation VI, both males and females can pass down moves and pass down the Hidden Ability. The female will pass down the Pokéball that it was caught in to its offspring. Example: a female Pancham caught it a Net Ball will always pass the Net Ball down to its offspring. Master Ball and Cherish Balls cannot be passed down.