Very sad, but it seems JG is merely putting his name to others work for financial reasons.
The Exchange had none of the usual drama and well crafted plots that we have come to love. If this was a first novel by an unknown writer, it would rightfully be dismissed as overlong, boring and without an ending, it just fizzles out.
If JG did write this, he should maybe think about hanging up his pen, personally I believe it possible that because his contract says he has to produce, he pays less gifted writers to do it for him.