The book plays out as each character has a crisis of some sort somewhere on the trip - which, in true pulpy fashion, is neatly tied up just in time for the junket to get back on board their plane and head to their next destination. There is a bit of a metaplot, and there are some clearly loose ends that will undoubtedly show up in later books, but perhaps moreso than in the previous three volumes, each story works as a standalone.
Also, this is the first volume that feels very dated. The series was published in 1988, and it really shows. Maybe it's my own nostalgia, but it definitely captures the grim feeling and political dystopia of the eighties. Perhaps this is because so much has changed in the last thirty years in some of the places they visit that the differences are more vivid.
Also, I noticed for the first time in this book that none of the characters' powers affect technology at all. Computers are mentioned a few times, but only to indicate wealth and status. Again, that's probably something that only stands out to an old nerd like me.