Agreed. The first book seemed just the right mix of gritty realism and fantasy. Yes, there was magic, but it had it's limits and the characters seemed human. The second and third books removed said limits to increasingly alarming degrees (to the point where one character actually flies) and the characters became cardboard cutouts (with the exception of Vi, but, while I appreciate what he did with her, I felt that her transformation was a bit to sudden, too rapid). Combined with incredibly poor decisions (like giving the ka'Kari a personality and voice, and returning you know who from the dead {I liked the character, but his death was an important plot point and added a lot of depth to the emotional interplay in the books. Bringing him back completely ruined that]), it all lead to books that barely resemble the first.
Overall, I think my biggest problem is that I see wetboys as a sort of specialized assassins, not something else entirely. I would define an assassin as anyone who discreetly kills someone for profit. SO wetboys fit the bill.