Questions posed by Regenesis include: is it responsible to colonize an "empty" planet for human use and turn it into a replica of Earth? What happens when one of the branches of government tries to take control, and it's the branch that you rely on to protect the citizenry? If we conceive of an unending line of Ariane Emory clones, at which point do they choose to clone Ari Emory II instead of Ari Emory I? Would that make a difference? And so on. Perhaps one of the problems with Regenesis is that there are too many questions, and Cherryh has to spend a significant amount of time reviewing events in Cyteen (and even events that occurred before Cyteen) to bring some closure to the characters.
Some of the questions that I wanted answers to after finishing Cyteen (see review) were almost definitively answered, including the "who killed Ariane Emory?" whodunit that has been with us for oh, 1000 pages. However, Cherryh leaves herself enough room, with Gehenna, Wintersnow, and the course of human evolution in the balance, to write a raft of sequels. I hope that it doesn't take another 20 years. Cherryh has cleared the slate to move forward into interesting and previously uncharted territory, and she has a compelling protagonist and cast of characters with which to explore some of the issues that are only touched upon in this book.
My ultimate conclusion: If you read Cyteen, you should read Regenesis. I give it a B+/A-