To some degree, this book makes up for the lackluster start to the series. It turns out that the story the author was setting up was somewhat different than the story she seemed to be telling at first. Whether that was the intent all along - or whether she switched direction midstream - I cannot tell.
The characters are the same as in the previous books (and are consistently written - so if you loved them before, you'll still love them, and if you hated them before, you'll still hate them). What changes is the focus - from 'plight of the malfettos' to a rather odd hybrid of 'these powers are destroying us' and 'we must save the world'.
But, hey, it made me cry. And any book that makes me cry can't be all that bad; it must have touched me on some level. Either that or I'm just a sucker for tragedy! Hopefully that is vague enough that it spoils nobody.