I'm a big fan of Cherryh's Alliance/Union universe from a long time back - it's very well conceived and grittily credible, and we get to explore it from many different perspectives and at different moments in time. 'Regenesis' is her first Alliance/Union book in many years and I'm afraid it shows.
In the meantime Cherryh has given us nearly a dozen books of her Foreigner sequence, set on and around the world of the atevi - basically, an alien race of samurai cats, speaking a complex inflected language inspired by Cherryh's expertise in ancient Greek. The Foreigner books are very formulaic and deliver the same kind of emotionally satisfying ending every time, which makes them great comfort-reading. Not much tends to happen in any one book, and the characters behave predictably, so they're a comparatively undemanding read.
This instalment-of-the-month ethos works fine for a multi-instalment potboiler, but less well when it's carried over into the author's long-anticipated return to writing Alliance/Union. Also evident is Cherryh's declining rigour in keeping track of continuity within the worlds she's created. In the Foreigner sequence this became obvious early on with the author's inconsistent spelling of atevi words and names, but in the most recent book or two we've also seen occasional wobbles regarding how things were back at the start of the series. In 'Regenesis' this problem is more acute - in places it's clear that Cherryh doesn't clearly recall what happened in 'Downbelow Station', even to the basic level of who was at war with whom. An editor ought to have picked this up.
I enjoyed 'Regenesis', but unfortunately for the same reasons I enjoy the Foreigner novels - its comforting serial ethos isn't the return to classic form I'd been hoping for.