This was a decidedly fun and enjoyable read. All the elements of a portal fantasy, creepy and evil far creatures, generally impressive world-building, a reasonable ending given all the characters. Novel does exactly what it says on the tin.
In many ways, this feels like a young adult fantasy novel for adults. Which is to say that YA is preoccupied with themes of...similarities and parallels between the reader and the characters in the book. YA often aims to build a relationship with the reader through this sense of kinship while literature aimed at adults that does such things is usually trivialized. Real adult literature defamiliarizes.
Which, of course, is a specious distinction left over from the early 20th century modernists and there is no reason to favor one over the other on the level of value judgement. It's a matter of personal preference and what you want books to do. Barker (rightly) wrote a book that appreciates that adults not only enjoy that moment when they recognizing a protagonist that is (like) them, but might enjoy seeing themselves and their concerns reflected in literature.
Although I will say that Nora's worries about her dissertation hit a bit too close to home.