The Relic Master/Book of the Crow series ends well, mainly because the arch-bad-guy gets quite a bit of on-stage time; a rarity in high fantasy. It's interesting to get a glimpse of his motivations and character. An alternative (eye-witness) version of events in the era of the Makers is presented - but how reliable is it? In fact it seems much more believable than the legends that have been handed down by the Order for many generations. This change of perspective on events reminds me of what happens multiple times in Ursula K. Le Guin's Earthsea books, where different view points and revelations about the past alter the reader's views on what has been going on, making everything much less black & white. Catherine Fisher does not reach the level of sophistication LeGuin achieves, but it adds a lot of depth to a world that is already realised in greater detail than many of her earlier efforts. Further revelations about the Sekoi also contribute to this.
The denouement is rather predictable in general terms and the aftermath is glossed over, which is a shame, because the aftermath is rarely examined in quest style stories even though it often presents challenges to the characters that are different and possibly more demanding than those of the quest itself. The state of the world at the end of many quests is dire and frequently a power-vacuum prevails. What happens then? The Scouring of the Shire in The Return of the King is the only example that springs to mind of trying to deal with this in a serious way. Since the entire primary plotline of the second book in this series is redundant, getting rid of it and having a book that follows on from the situation at the end of this book would have been much more interesting, with great opportunity for further character development in the two young protagonists.
Over all, this is one of Fisher's better series but none of the books individually is a match for her best books, such as The Oracle and Incarceron.