Robin Hobb has created a unique magic system in this world. There are two kinds of magics, the 'Wit' and the 'Skill'.
The Wit is an innate ability in humans that allows them to roughly communicate with animals, but if an animal also has the Wit there is a possibility to "bond" with that animal. Bonding allows both human and animal takes on each others mannerisms and allows the other to use the best of their abilities, i.e. night vision. With distance being no limitation the human and bonded animal can communicate to each other psychically.
The Skill is also an innate ability but it is strongest among the Farseer line. It is an ability to be able to communicate between humans psychically (only among those with the skill) and the Skill wielder can manipulate other people's emotions. At the most extreme, they can take over someone else's body.
The differences between the two (besides what is mentioned above) is that The Wit is considered a type of witch-craft and the general population do not like it very much. Whereas the Skill is considered to be of royal bloodline and therefore not witch-craft.
(Skip this next part if you do not wish to spoil the Farseer books. There are no spoilers for Fool's Errand)
Fool's Errand is the first book of the Tawny Man Trilogy. It can also be considered the 4th book of the Farseer because we still follow Fitz as the main character, instead it is 15 years later; Fitz is an middle-aged man and Nighteyes getting along in wolf years.
I found this book instantly grabbing my attention, and because I rarely read first person narratives I found it really refreshing. Hobb quickly re-introduces us to all her characters and how they differ from the earlier books. I had forgotten everything since the last time I picked up Farseer was about 2 years ago. The storyline in this book is about Prince Dutiful. He has gone missing, whether he has run away from the castle (been done before) or has been captured no one knows. Chade and the Fool convince Fitz into helping them find Dutiful. At the same time the people who have the Wit are being persecuted again, killed, cut into pieces and burnt over water (order not necessary) is what will await anyone caught practising the Wit.
What Hobb does really well in this book and her earlier works is that she strives to make the reader like her characters and for the reader to hate her villains. She leaves nothing out when re-introductions the characters and therefore I think it is not necessary to read Farseer to enjoy his Trilogy but I think the enjoyment will increase tenfold when Farseer is read first.
I couldn't put it down and read it in about a week. She ended the book very well, you know it is a semi-cliff hanger because it is the first of a trilogy, yet you could leave it at the 1st book and still be very content. I very much recommend this book.