4.5, rounding up because I love Jemisin and this series.  I did find this installment a bit unevenly paced, but this series is what I want in an urban fantasy: well written, creative, exciting, with the cities -- here simultaneously settings and characters -- coming alive (in the most literal way in this case).  Without a doubt, Istanbul is a highlight here, as are the relationships between the borough-avatars.  Cannot wait to see what Jemisin comes up with next.