Not badly written. The stuff with the little brother is poignantly told. Some of it is quite spooky.
On the other hand, this felt like a book in which very little happens other than the reveal of the ancient curse/prophecy…and it just…ENDS. Very much a “book 1” but even in a series, shouldn’t each book have its own purpose? I felt like this one really tailed off at the end in setup for book 2.
There’s something to be said for cliffhangers.