I would like to start by discussing writings of Brandon Sanderson in general even though I risk having a lynching mod of his fans showing at my doors. The guy writes fairly fast and he already delivered several complete series. I wish he would teach Speed Writing 101 to George R.R. Martin, Patrick Rothfuss, and J.V. Jones, but I strongly suspect they will fail the final exam. Coming back to Sanderson, he creates very original and interesting magic systems. He is one of the best modern fantasy writers when it comes to one-on-one duels/battles.
He also cannot write a good second book of a trilogy even if his life depends on it. His trilogies look like this: an excellent first book followed by unbelievably boring second partially due to a fact that he leaves the best characters behind or kills them. Finally the last book is an improvement, but still nowhere close to the first one in terms of excitement and quality.
This trilogy is one such example. The first book was an equivalent of a summer blockbuster movie (a good one, not recent generic superhero crap, or a reboot).
It contained a very memorable first line, excellent characters, great action scenes, and David's awful metaphors. The second book came. We left a couple of interesting guys behind (I challenge anybody to call Tia - who prominently featured here - at least two-dimensional character and she is as one-dimensional as they come), there was a lot of talk and minimal action, and David' metaphors became stale. It did not help any that Alcatraz from the similarly named series used them as well.
Finally we came to the last book. It does contain more action than the second one and the characters missing from the second installment made a much-needed comeback. In this sense it is a definite improvement. On the negative side the action lacked something that makes it really great and there were still lots and lots of mostly pointless talks.
As to the plot: after the events of the previous book the Reconers are few and scattered. The survivors keep themselves busy trying to neutralize a very powerful Epic (Epics can be briefly described as X-Men gone bad) who used to be their ally. Now the person in question just wants to watch the world burn.
I mean it literally. For starters the Reconers must get some equipment and to do so they need to infiltrate a stronghold of their previous supplier. In the trilogy "infiltration" means using lots of explosives and really heavy guns - the type that only very strong people can carry. From there they will have to move to a city made entirely out of salt (poor Atlanta).
I already mentioned that this book is better than the previous one which I rated with 4 stars. This also means I have to rate this one similarly as there is no way it deserves a perfect rating. Quite a few people said the ending was bad because the resolution of the main conflict was way too simplistic. I agree about the resolution, but I do not think the ending is bad; just unsatisfactory.
Some fun references follow. I mentioned Alcatraz used bad metaphors straight from David's collection. In this book one Epic used a talent straight from Alcatraz books: the guy could talk any imaginary language. Speaking about Epic talents, Larcener's one comes straight from X-Men's Rogue.
I still remain convinced the first book is better off as a standalone. Besides it did provide some closure.