The first of these was Lois McMaster Bujold, and Shards of Honor in particular. I'd never read any Bujold before. Now that I have, I see how ubiquitous references to her are in the interests, fanships, and common knowledge of many of my friends. Clearly that fanship is based in more than this one book however; indeed, several have told me that the books improve, but it's necessary to read them in order. Shards of Honor is primarily science fiction and secondarily romance. The resolution to the romance plotline is not the resolution of book overall.
The book was oddly paced: the first third was self-consciously fantasy-like, with analogies to princesses and dragons; the second third was space opera; the last third felt like a drawn-out epilogue musing on the consequences of war. There were appealing moments: Cordelia working around the system for a more efficient route; the running presidential joke, "I didn't elect him"; unexpectedly recurring characters.
fjm's other recommendation was as background reading, not science fiction at all. Apparently, some seven out of ten science fiction authors, on average, are Georgette Heyer readers. And I'd never read a single work by Heyer. The realization that references to Bujold among my friends are frequently was as nothing compared to the constancy with which I now see references to Heyer everywhere.
And now too I know why they read them: like so many others, I've found them addictive. I've read at least a dozen in the past few weeks, probably more, and am going strong. They're fun and funny and clever and romantic without being sentimental. They can be complicated and mysterious but always accessible, once the initial barrage of everyone having multiple names and titles is surmounted. Some are better than others, but there isn't a one I regret reading. My sense of compulsion about them was such that at one point when I'd run out of ones on hand and needed to finish another book I'd been reading instead, I begrudged it not being a Heyer novel.
* Today's entry falls squarely in the subgenre of Romantic Science Fiction. See previous posts in this series for subgenre details.