Inferno Squad serves as the prequel to the video game Star Wars Battlefront II, focusing on Imperial special forces soldiers. This novel fills the same role that Twilight Company did for the previous Battlefront game but has a few differences. The first Battlefront did not have a story mode so the characters were mostly generic Rebel soldiers. Battlefront II will have a plot, spanning from Return of the Jedi to The Force Awakens. Inferno Squad is the precursor to that game, taking place in-between A New Hope and The Empire Strikes Back. As such, the characters can be developed a bit further but only to a degree.
The members of Inferno Squad are shown in their first mission, christening the new Imperial black ops team. In the new Disney canon, the villain books have all been pretty good. Lords of the Sith, Tarkin, and Thrawn all did an excellent job of highlighting characters. But these characters had advantages the members of Inferno Squad do not. Tarkin, Thrawn, Vader, and Palpatine were all prominent characters in the old canon, cementing many of their character traits. Inferno Squad is a brand-new group of characters who must remain very Imperial over the course of the novel.
Sympathizing with the bad guys is hard. The aforementioned villains are all interesting for their own reasons. Palpatine is irredeemably evil, Vader has a tragic backstory, Tarkin equivalates ruthless with stability, and Thrawn is a tactical genius. The Inferno Squad members do genuinely believe in the Empire but more by their upbringing than due to personal qualities. Christie Golden could not do too much with them when they still need to be rigid Imperials for Battlefront II. It did help that the rebels they were fighting were more terrorists than heroes but they are still bland.
Other villains work because they are leaders who do not really care about morality. The members of Inferno Squad somehow convince themselves that genocide can be for the greater good, eating into Imperial propaganda. While Inferno Squad does not seem necessary to Star Wars fans overall, it will likely make Battlefront II more enjoyable (like the effect Catalyst had for viewers of Rogue One). It seemed odd for a book connected to shooter game like Battlefront to be about an undercover spy mission. Prioritizing characterization over action scenes is not necessarily bad but it just did not seem to fit with the game. For non-hardcore Star Wars or Battlefront fans, Inferno Squad can probably be skipped.