Much like Gears of war, Tome 1 : Aspho Fields, Gears of War: Jacinto's Remnant dives both into the "present day" storyline taking place between Gears of War 2 and Gears of War 3 as well as the prologue storyline taking place around Emergence Day. While not nearly as directly parallel as the two plots in Aspho Fields, Jacinto's Remnant helps flesh out another aspect of the Gears universe - the mood and cultural climate at both times.

Karen Traviss manages to convey this sense through the events in both times, namely the deployment of the Hammer of Dawn against the Locust in a way you might not expect as well as the migration of the remaining COG Nation to marginally safer ground than the compromised Jacinto. Both events shifted the attitude of COG citizens in major ways and thus shaped the way Hoffman and his Gears had to enforce a tenuous peace.

Ultimately, Jacinto's Remnant is a bit slower than Aspho Fields. Additionally, I prefer the character-driven focus of the latter book, though it's fairly clear that the second book's approach adds a lot to the universe in its own right. If you enjoyed Aspho Fields, Jacinto's Remnant is well worth a read.