Two things. First, the rating. I acknowledge this isn't an undying classic. If you're looking for science fiction with literary prose, go read Ursula Le Guin or Ray Bradbury or William Gibson. Or for the "Big Ideas" go to Robert Heinlein or Isaac Asimov or Arthur C. Clarke. What Bujold offers is different--characters you care about and want to spend time with, and in that regard, I'd say Mirror Dance is the strongest story in the series I've read yet--and given its Miles Vorkosigan is one of my favorite literary characters, I'd say it merits the five stars.
Second, even if this is one of the strongest stories in this space opera series, this is not the place to start. In some series, such as Marion Zimmer Bradley's Darkover, order does not matter--the books, though sharing a universe, are designed to be read independently. Except in a few instances, that's not the case with the Vorkosigan saga. You'll be confused, you'll encounter spoilers for earlier books, and the book's impact will be blunted. So I'd start with the omnibus Cordelia's Honor or Young Miles.
I probably should add one other caveat for those following the series--this is definitely the darkest work in the series thus far. Content includes sexual abuse and torture. Yet ultimately this is a great ride. In the last book Brothers in Arms we encounter Miles clone brother Mark. Not quite his evil twin, but as Miles puts it, at times his idiot twin. The very presence of Mark seemed almost farcial in the last book, and at first in this novel I didn't like him very much. But over the course of the book I did gain quite a bit of sympathy and fondness for Mark and for the ways he provided a great foil to Miles. And their mother Cordelia shines here as a kickass heroine every bit as formidable as her talented sons. (Her take on Miles at one point was hilarious and insightful both.) I'd say actually this is the one Vorkosigan adventure thus far where other character rival Miles in interest. A great read.
