My re-read of this series continues! Or rather, the re-read concludes, the first-time-read will soon begin with the hitherto unknown book 4.
This book really kicks the series into a higher gear. The first two had pretty good antagonists, mainly because of the clever plans they'd put in place before the books began, but this one has frankly terrifying ones. It also ties into the previous book much more, although I'm now realizing that this is more of a "shared world" than a tight book series, especially as the non-David-Drake co-authors (who are different each book) seem to be in the driver's seat.
The main female is also much more of a force here than in the previous two. The others fell into the "intelligent, beautiful, spunky, loving" category familiar from 60s authors like Heinlein, who were an advance on earlier heroines because they showed how worthy they were of being rescued rather than being totally passive objects, but still at core were just an adjunct of the hero. The character of Suss here, on the other hand, is more flawed and more powerful, at many times (including the final fight) putting herself at the center of the action and the danger and facing the consequences herself.
It also continues the speculations about space warfare and space politics, and takes one piece of technology ubiquitous in the first two books in a whole new direction. The primacy of the horror plot (and some new technology tying directly into it) leaves less room for the Imperial stuff, but the tradeoff is worthwhile.
It doesn't quite make 5 because it peaks about two-thirds of the way through, and because there are considerable plot questions unanswered. But I'm looking forward to the fourth book more than ever, while being very glad I didn't rely on my 20+ year-old memories of the first three.