One word to describe this book (and series): Amazing!
In the fifth (and final) book of the Fablehaven series, the battle to keep the demon prison Zzyzx closed comes to a conclusion. The Knights of the Dawn are fighting to find and protect the remaining artifacts, while the Society of the Evening Star continues to seek them out. Kendra and Seth are once again thrown into the middle of the conflict, and must use their unique gifts and abilities to save the world from destruction.
Once again, Mull does not disappoint! This book is filled with action, suspense, and humor. Despite the 500+ page count, there is not a dull moment. The book is evenly paced, and the action builds and declines multiple times throughout the novel.
If I had to pick something to criticize it would be Mull's tendency to create "throw away" characters. Often (in most of the books of the series), the Knights are about to head off on a mission and we are introduced to (sometimes multiple) new characters. Usually, one or all of them end up dying shortly after. Once you get used to this pattern it become pretty easy to predict that the character whose name you just learned is going to die in about 15 pages. However, since he doesn't always kill them off, and occasionally the more established characters have been the victims it doesn't bother me that much. I'd rather the characters I'm not attached to die than my favorites anyway!
Oh, and one other small complaint (*spoiler*) - I wish Bracken's speech to Kendra at the end had been Kendra's speech to him! It would have been good for her character to finally be assertive and strong by telling Bracken that she likes him, but that she needs some time to herself; and that he can wait for her if he wants, because after all the years he's lived he can certainly wait a few more, if he really cares about her. And she also should have kissed him before the big battle that they all thought they were gonna die in. Because that would have been funny. Just plant one on him and say, "Alright, I'm gonna go slay that demon for ya!" (*end spoilers*)
All things considered this is one of my favorite series. It's right up there with Harry Potter and Twilight (yes, it's that good!). It could appeal to both boys and girls, and really, readers of any age. I only wish it was more well-known that it is! Maybe if a movie does get made (last I've heard is sometimes in 2011), the series might start getting the recognition it deserves!