Fool's Assassin is Robin Hobb's fourteenth novel in the Realm of the Elderlings books, and although so far I'd say you could probably get away with just reading the other Fitz trilogies before reading this one (The Farseer Trilogy, The Tawny Man Trilogy), you definitely wouldn't want to leap straight into this.
The most important thing for fans to know about this book is that, although the Fool gets equal billing in the title of the series, he's not on the page much in this book. Don't think that this is his story more than the Tawny Man trilogy is. In fact, there is in general a lot of building in this book and it mostly focuses on Fitz's family relationships and daily life.
That is not to say that I don't like this book. I do. Robin Hobb regularly rips my heart out every hundred pages or so. The Realm of the Elderlings is, as always, fascinating, and her characters are a pleasure to spend time with, even when one wants to shake them. I remember a LiveJournal community called fitz_is_stupid. Fitz remains, in some respects, rather stupid. I don't want to include spoilers for a book well into a series in a review published months before the release date, so I'll just say that something happens less than halfway through the book that seems rather obvious to me, and which Fitz has seen all the evidence for, that he still hasn't gotten at its end. But he is Fitz, and even though he's been well trained in observational skills of the kind that he uses when he reports to Chade, he's still amazingly oblivious in some areas.
This is very much a latter book in a series and the first book in a trilogy. Starting here wouldn't give you a good entry point, and stopping here without the intent to continue wouldn't be satisfying. If you're the sort of person who sometimes can't handle waiting for sequels, this might be a good series to wait to be completed before you start. As for me I'll be on the second book as soon as I possibly can.
Overall Grade: A
Fool's Assassin will be available August 12