This book is as much a coming-of-age story for Yarvi as it is the story of intrigue and war over a throne. At the beginning, he knows little outside his life in the nobility and his studies to become a minister - an adviser to kings and member of the Ministry, similar to the medieval church. But as events throw him into dangerous situations, he's forced to grow up quickly to survive. It's by no means an original formula, but I thought it was executed well. It helps that Yarvi is a very likable character - he has his flaws, but on the whole he tries to hold to his word and do right by his friends.
Much of Yarvi's story involves significant suffering. He's thrown into slavery, nearly starves and freezes to death, barely survives attempts on his life, goes ill-prepared into battle, and so on. It's all described in quite a bit of detail, though I don't think the writing is overly graphic. There's a gritty realism to the descriptions, though, that may not be for the faint of heart.
The world that Abercrombie has built is medieval with few, if any, magical or spiritual qualities beyond human belief. There are hints of some great cataclysm in the distant past, which could mean that some sort of apocalypse created this world in the far future of our own. It doesn't really matter much, at least not in this first novel. I expect the other books will reveal more of the world, possibly including its past.
I had a good time reading Half a King, and I'm looking forward to the following books. Recommended for anyone that enjoys the genre.