WORD OF ADVISE:
The Player Companion line is not really checked thoroughly enough for balance or mistakes of the new content, because the monthly release window is too narrow for that with all the different contributors per book.
As a result there is a lot of power creep and sometimes a few underpowered things.
All in all one has to pick the Player Companion that appeals to him/her.
You should check with your GM for permission to use the new content though.
As a GM i would roughly allow half of the PCs content and ban the other half.
Being a Pathfinder Player Companion Subscriber, I disagree with this blanket statement. Do they make mistakes? Yes. Editing errors are made, including giving differing archetypes the same name. That has happened a few times.However, power creep seems to happen more in 3PP than in these Player Companions, in my experience. Often, these options are more flavorful than optimized.
This is my favorite line of all of Paizo's products because many contributors are not part of the Paizo staff and therefore have some fresh new ideas (as do the Paizo contributors, also) not seen in other parts of the game line.
While $15 is a fair amount to pay for a 32 page book, I have yet to regret subscribing in the year or so I have subscribed (I think it will be a year in January?). Love Player Companion!