Anyone who has been reading the books hoping desperately for a happy ending is unlikely to be satisfied, and I was personally somewhat disappointed by the deus ex machina quality.
Overall, it's a different sort of book. The saying is that the point of a story is the journey rather than the destination; this book is a perfect example and perfect counterexample in one. Reaching the destination is unlikely to make the reader particularly happy, but does bring a sort of catharsis; and anyone who can reach the end of the book without feeling strongly for the characters is probably a sociopath.
Probably not a good book for moody teenagers.