A new review over at Tor.com:
Last January’s Empire Games kicked off a new, standalone chapter in Charles Stross’s Merchant Princes continuity: a science fictional thriller involving panopticon societies, multiple timelines, a cross-timeline Cold War and nuclear-armed standoff, political crises, and family secrets. It packed a lot into a relatively slender volume. As its sequel—and the middle book of a trilogy—Dark State has a great deal to live up to, and even more work to do.
It succeeds admirably.