I really am enjoying this series, and the books are starting to get into an overall arc it seems.  The first three were more or less stand alones.  I also love the jumping back in forth in time that the series does.  This is one of the few authors who has really pulled that off well.  It allows the characters that get killed off in the first book to stick around for the rest of the series, and they continue to develop.

Audible Link