I've read some reviews that call this Harry Potter for Grown-ups. I have to say, Harry Potter is Harry Potter for Grown-ups. Speaking as an adult, I didn't need that re-written for my age group. (This complaint is leveled at reviewers more than at Grossman, though the marketing is at least partially at fault, too.) 
 I feel like this novel needs two reviews: 1 star for the first two-thirds and 4 for the last bit. I read the first novel, The Magicians, when it first came out, pre-Good Reads, before I recorded anywhere how I felt about particular books. It took less than a chapter of the Magician King to remember all of those things I found annoying about the first novel - its 'what-if-I-replaced-wonder-with-cynicism' approach to re-imagining the Narnia novels. The characters, many of whom return for The Magician King, battle to come up with the best Dorothy Parker cutting remark more than they battle for top marks. None of these characters are people you want to spend a lot of time with and they seem not to have grown out of it by the time they become kings and queens. 
 Didn't take me long to remember that I was pretty satisfied with the ending of the first book. Satisfied not in that I'd completed a good novel, but in the sense that I didn't feel like I needed any more of it. Sated. 
 Grossman let all of his characters continue unchanged for a good long time, but then it got better. While Quentin failed to evolve sufficiently in the first book, the threat of losing his kingdom, and the magic that makes it all possible, makes it more dear. Alternating chapters of Julia's past and path to magic adds another nice arc to the novel, from put-upon brat with more chips than shoulders to someone who has earned something and values it properly. 
 Then the novel develops into a good questing adventure story. Quite engaging, really, but in the end I'm left wondering if there's enough here to make me continue with the series. 
 I'm also reminded of Joe Meno's novel, The Boy Detective Fails, that I read a couple of months ago. As weird as it was, one of the elements I most loved about it was how much Meno respected the inspiration for the novel. As much as there was to mock about the Hardy Boys or Encyclopedia Brown, this was no parody of those forms. Grossman's is often mean-spirited in his translation of situations from Narnia or Harry Potter, which is frequently name-checked by characters in put-downs of other characters. There's a softening of this approach in the latter third of the novel that might make me pick up the next, but I think it'll take some convincing.