Chuck Wendig had a pretty hard road ahead of him when he took upon the Aftermath trilogy as he, essentially, had to replace the entire Star Wars Legends Expanded Universe by creating a history that replaced the 100+ books which chronicled the period from the Battle of Endor to when the Empire finally surrendered in Timothy Zahn's Visions of the Future.
Wendig's task was somewhat mitigated by the fact that instead of a twenty-year guerilla war by the Empire's remnants, it's a much more sedate six months between the death of the Emperor to the Battle of Jaaku where the Imperials are defeated. Still, his three books received a good deal of criticism for their focus on new characters rather than Han, Luke, and Leia as well as minor interludes. Still, I was looking forward to how the book wrapped up the plots and what hints they'd give toward the rise of the First Order.
The premise of the book is Gallius Rax, agent of the deceased Emperor, has successfully scuttled attempts by the New Republic and Empire to make a peace treaty. He has also withdrawn all of the Imperial fleet to the planet Jakku in hopes of setting up a massive conflict between the two sides. Grand Admiral Rae Sloane, stripped of her position, now hunts him with ex-Rebel Brentin Wexley. Huntin them both is Norra Wexley and her crew who believe Sloane masterminded Rax's terrorist attack on the New Republic Senate. Meanwhile, Mon Mothma fights an attempt by a rival Senator to seize her position after the attack makes her look weak. Eventually, they will all meet up at Jakku to decide the final fate of the galaxy.
Ultimately, I think the book did a decent enough job of fulfilling its primary purpose in explaining how the Empire was brought to its knees. Gallius Rax has been suspected of running a con against his own troops for some time and the realization he's been working for Emperor Palpatine the entire time in order to initiate a "scorched Earth" policy similar to Hitler's is a neat bit of storytelling. It also fits that Palpatine would set things up that no one could inherit his throne save, perhaps, a Sith Lord like Darth Vader who would suspect such a thing. This truth is revealed early in the story and a pleasant surprise as I was of the mind Rax would turn out to be an agent of the still-mysterious Supreme Leader Snoke.
I also like the examination of the trouble the New Republic is having in defining itself beyond being against the Galactic Empire. Mon Mothma is determined to make the Empire's existence almost incidental to them while her opponents believe destroying it is their primary concern. Honestly, I think Wendig is a bit harsh on the side which believes you can't build a new government until the old one is completely dismantled. Indeed, the ending to that plotline with Mothma's rival leaves a lot to be desired. I think the heroes' position also changes several times in order to accommodate whatever is convenient for the story and keep our sympathy. Ditto, the "villains" operating on Chandrilla.
Of all the story arcs in the book, I have to say I liked Rae Sloane's the best. Mostly because it doesn't go in directions I expected. Continually, she's confronted with the Dark Side (*rimshot*) of the Empire only to try to make excuses like it was Gallius Rax's doing or that Palpatine was the real problem. It's interesting, also, to see how Imperial ideology has twisted her even when she's one of the more "sane" Imperials. Indeed, that sanity blinds her to the faults of other members of the organization. How it ultimately resolves leaves me thinking about her character in ways I don't normally with Imperials.
I have to say I actually liked the character of Norra Wexley as a protagonist far more than I expected to since I considered her story somewhat boring in previous books. As the unwilling single mother with a teenage son turned guerilla fighter, she's a character who has had her own emotional journey throughout the story. Norra isn't a Jedi, determined to do the right thing, nor is she a bad person. It makes her story all the more personable. I even started liking her romance with Wedge Antilles, even noting that she's probably about fifteen years older than him. Which, hey, isn't a big deal. Love where you will.
There's a couple of areas I didn't much care for: the aforementioned handling of Mon Mothma's rival (you, sir, are no Borsk Fey'lya) as well as the fact Wedge Antilles seems to be written as a midle-aged man versus a man barely older than Luke Skywalker. I also think Sinjir, a former Imperial interrogator, getting a position as high as he does at one point is straining credulity. Still, I overall liked everything in the book and enjoyed quite a few moments I wouldn't have expected to. For example, Jar-Jar Binks makes his first cameo in years and it actually fits as a final fate to the character. That, alone, was worth the price of purchase.
In conclusion, I have to say this was a very entertaining book. It's not really a great substitute for the Legends Expanded Universe but it fulfills its purpose in saying, "So, what happened to the Empire after Endor." Gallius Rax was an excellent villain, Grand Admiral Sloane was well-written, and we got to see all of the arcs of the series' characters wrapped up. Could it have been better? Maybe. Maybe a series centered around Han, Luke, and Leia would have been better but I enjoyed this for what it was.