The book is really sad, I must admit. Here we have two surviving Andalites from the great Dome ship battle at the start of the series, and one is dying and the other is being held hostage by Visser Three. The two are very best friends, like Ax and Tobias are, but the problem is that they are trying to avoid the Animorphs' help and that only causes problems. But what I want to know is why Marco has to tell the story. This is a little too heavy for his type of character, and there is very little humor in it. But I guess it's because he has just come off from the re-marriage of his father that KA thinks this is okay. It's excusable, though, but a little unnatural.
I don't feel that this book is among the worst of Applegate because it has nothing to do with the main goal of the series, but because the story is really touching and a little depressing that you have to like it. But I agree that KA should not forget about Mertil, the Andalite who will be alone when his friend dies, because she is adding so many branches into the series now it's going to be pointless for even putting them there is she isn't going to bring them back up in the future. Other than that, this book is good.