I just got the book for my birthday (I'm including it in my birthday book haul)! I can't wait to read it, even if I have an intense hatred of love triangles! :)
I was kind of on the fence about this one as I, like you, really enjoyed the mythology aspect but I thought Twylla was a really inactive character for the first 60% of the novel, as in she just goes along with what the queen says and doesn't make much of her own choices in the beginning part. Then at the end when everything is revealed then she becomes more active. I kind of wish that she had been active for a larger portion of the book. I also agree with you on the love triangle aspect and i really don't like seeing them in every single YA book. If they were sporadically placed into one or two series and not every single one then i'd probably be more open to them.
I feel like I'm the only one who hated this book, the guard/prince love triangle has been done so many times and has been done 100 times better, the writing wasn't good, Twylla was a really annoying character (I love strong female characters, which Twylla was definitely not) and I also hated Lief, the only character I liked was Merek. The author ruined the only thing I liked about the book, Twylla's ability.