Partly it's the sense of recognition. I've never lived up there, and I've only been to Prince Rupert once and onto the highway a handful of times, but Unmarked gives you a version of BC I'm comfortable with, from growing up in the Thompson-Shuswap myself.
Partly it's just fun to watch a young(er) writer using almost the whole toolbox. She deliberately cuts out commas in lists, for example, to express movement and to emphasize both the simultaneity of experience and the running together of memories. Some essays are in the second person, too, which is always fun, though most are in the first or third.
But mostly it's the intimacy of it, the sense of real youthfulness in these recollections. It's an adult writing from within an experience that no longer envelops her, but with a very sure hand. The persistent references to teen fears of pregnancy, for example, and to alcohol; the rough deaths that happen in small towns; the keen childhood observations that impose no judgment on what's seen: these things involve me in the book.
I'm looking forward to teaching Unmarked!
For a bit more, check ABC Bookword. For a really great post, see rob mclennan on de Leeuw and Stan Dragland.
(Unfortunately it does suffer from weak editing, which can happen at small publishing houses. Spelling counts, and even when an author submits a mistake, an editor needs to catch it: NeWest Press needs to keep an eye on the person assigned to this book, I'd say.)