First, ask yourself, what is the purpose of a Player's Guide? It's to tell the players what they need to know about a campaign. That includes providing information about the location they'll be visiting and providing potential hooks for their characters.
This does a little bit to provide hooks in the way of campaign traits. There are a handful of suggested traits that would give the PCs a reason to be in Sandpoint, and some of them are very powerful -- I'd say they should almost be feats instead.
After that, there's very little useful information for the players. There's about nine pages' worth of descriptions of locations that the players will never visit unless they go completely off the rails of the campaign. There is very little information about the actual culture and history of Varisia as a whole. There's a map of Sandpoint, but the actual description of Sandpoint is only two sentences long. Your players will find themselves asking, what roles do the different races and classes play here? What deities are commonly worshipped, and what role does religion player in your average citizen's life? What languages are commonly spoken? What is the (known) history of Varisia like? What types of unique equipment or creatures are found in the area? The player's guide does not provide answers for any of these questions.
In short, they're better off just reading the original player's guide and skipping this one.
I just finished playing through this module, and we really enjoyed it. It's fairly open-ended and sandboxy, but still gives the players a good idea of what they need to do to accomplish their roles. It also makes good use of incorporating the Harrow Deck, and players who like props in their games will have fun searching the deck for the appropriate cards.
There's also a lot of room for roleplaying, considerably more than most pre-made modules I've been through. Almost every encounter has a fair amount of roleplaying that goes along with it, and many of them can be talked through with no fighting at all. Characters who focus on social skills will get a lot of use out of them. On the other hand, there's always a way to progress by picking fights, so groups that just want to hack things up will still have fun. There's a lot of variety in the encounters, and practically any type of character will have an opportunity to shine.
The way the combat encounters are set up is my largest complaint, though; the players typically have two or three days between each encounter, and most of them are against a single powerful enemy; or at least, if there are multiple enemies, there will be a boss and several smaller enemies that don't really matter. If the party has a character that is capable of going nova or if the boss just gets unlucky on a saving throw, the party may tear apart several of the "big" encounters in a single round. There are no smaller encounters to deplete the party's resources leading up to the big fights until you get to the very last part of the module.
A smaller complaint is that the plot hook is really completely irrelevant to the overall story. A random NPC gets sucked into this world and the players go in after him; he doesn't have anything to do with the story inside the realm, the players don't interact with him at all until the very end, and he really is almost literally just a hook to get the players involved. By the time our group was about halfway through the module, we had forgotten we were even looking for him.
Still, it's easy to recommend this module to pretty much anybody. It was a lot of fun.
My group had fun with this overall, but it's got a few problems, largely due to being much more difficult than your average 8th-level module. I had a party of four fairly skilled players, and there were two deaths and several very close calls over the course of the adventure -- I could have easily caused a few more player deaths if I had the enemies finish off unconscious players rather than pulling their punches and moving to a new target after somebody went down.
It starts off in an exotic local with lots of interesting flavor, and the roleplaying aspects of it are pretty fun. There's some mystery, some investigation, and some interesting cultural experiences. The investigation is probably the best part of the module, and will take up about the first 1/3 to 1/2 of it. There are some fun NPCs, and at 8th level the party probably hasn't dealt with shapeshifting outsiders before.
Then the combat encounters start, and almost every single encounter in this module has a CR that's above the party's level. Some of them are significantly above the party's level, and near the end the party may have to fight several of them in a row. There is relatively little opportunity for roleplaying for the rest of the module. There are also a few encounters where the enemies have tactics that are decidedly not optimal, but you really need to run them as written, because if you have the enemies use a bit of strategy, they'll destroy the players -- I have no doubt that there would have been a total party wipe if the enemies had gone all out rather than behaving as written.
Overall, I liked it, but you'll want to tone it down if your party doesn't like being brought to the brink of death in every fight.