As I wrote in my review of "The Magicians," this series is probably much better if you're a former fan of the Harry Potter/Narnia/etc books than if you're a current fan or indifferent to that genre.
Being pretty indifferent to the whole "Young Adult" fantasy superbestsellers thing, I regard this as a competently written and entertaining parody/homage. Perhaps the genre references and in-jokes are a bit thinner on the ground here than they were in The Magicians, which IMO makes this a better read.
On to the particulars: This volume owes less to Harry Potter and more to Narnia than the first one. Worldbuilding is a bit thin, as the author touches on several universes, each of which was more or less interesting in itself but not very fleshed-out. This book is mostly about the characters, and if you can't relate to a bunch of gifted but terminally screwed up twentysomethings you probably won't get much out of it.