This novel is about 1/3 new, exciting content. 1/3 of the novel is references to the other books in the series. The last third is made up of new, but confused stuff that cleans up the plot and sets up the next book.
The Dragon is an interesting villain, and the Widow is at least scary. Watching them interact with the characters is enjoyable. While they seem to be fairly deep well developed characters, the story doesn't really use them for anything other than to be bad guys. As the story progresses they appear less and less important except that they give the rangers something to do.
Then the author ramps up the page count massively by having every character dwell on the last two books constantly, and when the characters aren't thinking about what happened, remarking on how they have changed/how things should be done differently now that they have learned from the experience, or thinking about how other characters must feel about what happened, the narrator is reminding the reader what happened to them in the last two books. If the reader had forgotten or never read the books it might have been helpful to introduce the story, but it never ends. There is no point at which the author goes, "Ok, you should be up to speed now, enjoy the rest of the book."
Hood not only takes on the Dragon and the Widow, but also confronts several enemies from his past who just happen to be around being angry with him. Also, there is a new enemy rising in Germany who will probably appear in the next book or something.
There are so many enemies, and so many characters, and so many backstories the book just gets bogged down. The book is so crammed with stuff that nothing really seems to matter that much because the author can't afford to spend any real time with any one plot or any one character, and squanders pages by relating and sometimes re-relating the events of the past books.
Overall it was a decent read, but not one that I would very strongly recommend.