I am reviewing this book after having read the entire trilogy and what I say goes for all of them. The author had a really, really great idea, very compelling and highly original, as well as a writing style I can best describe as haunting. But I think she failed to deliver the truly great story that this trilogy could have been.
At the core of the story is a pair of twin sisters that are the focus and instruments of an ancient and eternal battle between good and evil. They are supposed to work together to fulfill an ancient prophesy, but they find themselves choosing different sides, each making a surprising choice, basically taking on the other's job. At some point they discover a connection to a hidden magical community, living in a cloaked island, a society quite set apart from their own world (Edwardian New England).
Frankly, this community was the main probelm of the story. It was reminicent enough of "Mists of Avalon" to sound derivative, and therefore unoriginal, but it was not a direct reference to the Arthurian tradition, so the reader did not get an immediate recongition of it. The result was to have the watered-down description of a faint copy of an Avalon-esque society that was familiar enough to be boring, but not familiar enough for the reader to connect to it. This might have been adressed in a much longer trilogy, where the author would have time to describe this society with detail, but, as it was, we ended up with something that felt like a pastel drawing of an oil painting; pretty enough, but weak, pale, without vivid colors or depth.
This is a great pity, not only because the core idea (the twin sisters, the ancient prophesy about them) was brilliant, but because the story and the characters outside this Avalon-lookalike place were very well drawn, charming and compelling. I cannot help but feel that it would be much better if the author had resisted the foray into Arthurian legent and stuck with the "real" world.
For the rest, the story was quite well-written, but I confess certain repetitions grated on me. The most annoying one was the constant use of "even still" in place of "even though". English is not my first language, so I am not sure if this is grammatically correct, but as it appeared too often to be a typo I can only assume it is. But even if it is grammatically correct, it was used so often (practically in every other page) it got on my nerves.