Whoah! I wasn't expecting that!
Initially I was a little disappointed because the much heralded return of BoB Howard as narrator was not as much as fun as anticipated: his distinctive voice seems to have largely disappeared. To some extent this is understandable since he's ten years older than when he first appeared, has seen an awful lot of horror, terror, death and destruction and has also ceased to be entirely human - but his nutso forms of expression were a great part of his appeal.
Later revelations and plot developments were so unexpected, shocking and game changing in terms of the series as a whole that, in fact, this book re-invigorates a series that was flagging and makes me more excited for the next volume than I've been for quite some time. Props to Stross for taking the series alarmingly far outside its comfort zone.