Not a great book, but not bad, either. It’s your standard child of a book collector finds something interesting and gets involved in something big and fantastical, all revolving around a book. (If you don’t think this is a trope, you’d don’t read the same books I do. Which, come to think of it, is probably why you’re reading this. Either that, or you’re my friend.)
Note that I’m not complaining about the trope – I love books about books – but it just was a fairly mediocre entry into the annals of the genre. The kids were okay – twins just turning thirteen, who don’t get along – but the adults were pretty flat, especially the overprotective best-friend-of-dead-mother. The plot does manage a few fun twists, one of which is actually fairly brilliant. Overall, it was a fun, quick read, but you probably don’t need to go out of your way to find it.