For starters this book is nothing like the psychic rules that polarized 3.5. This unique approach to occult adventurers bring a new approach to many old and loved tropes.
Back when 3.5 first stopped being supported by Wizards of the Coast, Pathfinder excited me. Since the initial release of the Pathfinder Core Rulebook I have obtained a copy of every hardback book they have released. None have excited me as much as Core until now.
This book introduces amazingly distinct an new classes. I can't really say this class is like a combination of these other classes because, for the most part the classes are all very unique. This is accomplished both by using mechanics that are new and spell effects that have not been seen before in Paizo's books.
I personally love the Kineticist and the Medium, both designed by Mark Seifter. The Kineticist is the elemental damage specialist we have all been waiting for since sorcerer fist came out. This class can consistently pump out respectable damage, and if you are willing to lower your hp for the day also nova out some impressive abilities.
The Medium is the jack of all trades, but only one at a time. A with careful planning, and the GM allowing you to find the right place to hold a seance, a medium can fill most gaps that a group may have, and change his specialty day to day depending on what is needed. This class will do phenomenally well in the PFS environment where scenarios what the party needs changes from group to group, but even in setting where your groups abilities are known constants the ability to tailor your roll for the day is not to be underestimated.