As I noted in my first comment, I found Santiago a fun and light read. But it does bug me when I come across something that doesn't quite make sense to me (in the context of a book).
The first one was the conversation between Virtue Mackenzie and Sokol (p94) when Sokol refers her to the Swagman. I found it very odd that he would do this when I read this. This got me thinking about attributing motives to story characters which make sense to the reader. As Sokol deals with Santiago (p98), I can't understand his motivation and can only contribute it to a plot device to move MacKenzie forward in her hunt for Santiago.
The second is the conclusion/epilogue, which I found both disappointing (Cain getting killed, although I guess that was only a matter of time), and illogical: 1. Why would "Santiago" stay on Safe Harbour? and 2. Mackenzie becoming famous with her interview makes her a prime target for every bounty hunter in the galaxy; a jab of Niathol (p70) and she spills the beans.
But perhaps I am taking it all a bit too seriously!