On one hand, Predator’s Gold does a solid job of expanding on what was the best part of Mortal Engines: the world building all around mobile cities that eat one another. We get to see a few more cities–both predators and trading cities–along with more details on airships in this world. But the real worldbuilding gold1 is in the parasites that can attach themselves to cities and steal from them. It really makes the cities feel like gigantic living organisms as much as anything, which I’m sure is Reeve’s intention.
On the other hand, I very nearly put Predator’s Gold down several times during the first half of the book. There’s a rather blatant love triangle between Tom, Hester, and Freya (princess of Anchorage–roving city of the north nearly destroyed by a plague in the recent past). It really doesn’t make much sense given Tom and Hester’s relationship at the end of the first book and drags on way too long. Perhaps that’s what some people read the book for… but it’s really not for me.