Every so often you come across a bestselling book, and simply don't comprehend the hype (you can probably guess where this is going). 
 If I had to describe Prince of Thorns simply, it would be as "Grand Theft Auto for the Grimdark Fantasy generation". Our protagonist/antihero is Jorg, a 14 year old prince-turned-mercenary, (for which read: rapist and murderer) slaughtering his way through a fairly standard vengeance quest. Spiteful, violent and impulsive, he launches himself into confrontations without the barest hint of a plan, relying upon his "genius" (read: luck) to get him out of trouble. We even find out later that it's not that Jorg is lucky at all, he's just (view spoiler)[under the control of an evil sorceror, who guides and nudges Jorg's decisions, robbing him of agency of most of the book, and removing any sense of achievement from most of his victories) (hide spoiler)]. As an antihero he felt horribly obvious, particularly when compared to other fantasy examples, such as Joe Abercrombie's Glokta, or Stephen Donaldson's Thomas Covenant. 
 Mark Lawrence writes well, and Jorg's caustic personality comes out well in the prose (although I must say that I didn't really buy him as a believable 14 year old - even less so in the flashback sequences when he's 10). Other characters are generally served less well. We have Katherine, a princess and love interest, who appears for one scene, and becomes magically emotionally significant to our protagonist (if Lawrence had leaned more into Jorg being a 14 year old, I might have gone with it, but other than the mood swings Jorg's defining characteristic seems to be his preternatural maturity and intelligence). There are a couple of generically evil wizards, a cruel father, and then an assortment of mercenaries who are generally all allotted a single character quirk apiece in place of a personality. This is entirely functional adventure fiction, but I think the hype unfairly raised my expectations here. 
 The most interesting aspect of the book is definitely the world-building, where Lawrence has created a fairly standard fantasy world (kings, knights, castles) in the future ruins of our own Earth. Jorg reads Plutarch and quotes Nietzsche; Jorg's father resides in a keep built from the ruins of an old sky-scraper. It's fun, but it has been explored with greater depth and nuance by both M John Harrison's Viriconium and Joe Abercrombie's Shattered Sea trilogy. 
 As a side bar: Prince of Thorns is an excellent counter-illustration for Sanderson's First Law of Magic. Lawrence never really explains the rules or limits of magic in his world, and the future-earth setting somehow robs it of mystery and awe. As a result, Jorg's success and failures in the fact of magical foes feel generally unsatisfying. 
 I might have enjoyed this all a lot more when I was a teen (and there are certainly books in this world that ought to be read when young). This is a perfectly decent bit of adventure fiction, but it's not really what I look for in fantasy these days.