The Best of All Possible Worlds is a marvelous science fiction love story. It's more science fiction than romance novel, but the strong love story at its core should keep any romance/science fiction fans more than happy.
This is the story of Grace (a Terran) and Dllenahkh (a Sadiri). Grace is a native of the planet Cygnus Beta. This planet has become a home to several groups of interplanetary refugees. There are four different alien groups (Terrans and Sadiri included) in known existence. They are distantly genetically related and have settled on several planets.
Dllenahkh's people are the Sadiri. When the Sadiri's home planet is destroyed, many of the survivors settle on Cygnus Beta. While Grace has various complex scientific jobs, it's simplest to describe her role as one of cultural liaison between the refugee Sadiri and Terrans, who are the dominant group on Cygnus Beta.
The Sadiri are a race that values intelligence, logic, and minimal display of emotion. They use meditation to control their telepathic skills. They are anxious to preserve their culture and challenged by the fact that most of the surviving refugees are men, which not only makes it difficult for them to form family units but also destabilizes their whole society. Fortunately, Cygnus Beta is home to many sub-cultures of taSadiri - Sadiri who long ago left the home world and who do not practice the mental disciplines of the Sadiri. These groups of taSadiri live all over the planet in very different settings and with very different cultural adaptations. Dllenahkh and Grace are part of an expedition to contact these groups and see if any women would be willing to become Sadiri wives. Alien road trip for the win!
I would not describe this as a romance novel. The romance develops subtly, almost in the background, and because most of the narration is from Grace's point of view, Dllenahkh is fairly mysterious throughout. However, even though lots of other things are happening besides the romance, the romance is really the core of the book, and it's a lovely one, full of slow built trust and understanding, warmth, compromise, communication, and humor. Also, it contains the hottest hand-holding ever (except for Mulder and Scully in "the X-Files" - they hold a world record as hottest hand-holders in history).
One of the things I loved about this book was its celebration of all kinds of love and its examination of many kinds of communities. Grace is very non-judgmental as long as communities and individuals do not cause harm to others. She is willing to sacrifice her own happiness and her own career to protect others from exploitation, but if everyone seems happy then she has no issues with how they become so. There are monogamous couples, casual relationships, same-sex and group marriages, people who choose to remain single, and a character whose gender is not known (and it's considered very rude to ask). Its also noted, frequently, that the scarcity of females is not just a problem for the Sadiri because they need sex partners. They need grandmas and aunties and sisters and friends. I do not intend to suggest that a female is valued only in the light of her relationship to men. Women are highly valued professionals and leaders - there's no pervasive sexism in the workplace, and the Terran community of which Grace is a member is matriarchal.
Some readers have pointed out that the description of the Sadiri, plus the destroyed home world, is very similar to the depiction of Vulcans in the 2009 Star Trek movie. However, while the concept of a stoic and logical race is familiar, the rest of the book isn't Star Trek-y at all. I've seen some commenters on other sites be skeptical of the book's premise, suggesting that it must be high-level fan fiction. On the contrary, this is a marvelously original book. It is a great example of how you can do science fiction that is character oriented and it's also a great example of how you can do a science fiction book that isn't all about action, without its being dull. As subtle as the romance is, it left me with that little happy sigh that always gets a book an A grade from me.
I was disappointed by the cover. I like that it is subtle and evocative, but I dislike that it makes the main character look pale and blue-eyed whereas she is actually dark skinned and brown-eyed. I applaud diversity in books and it bothers me enormously when covers whitewash their characters. Diversity of all kinds is celebrated in this book. It's basically the point of the book. I wish the cover had reflected that. Cover aside, this is a great love story for science fiction fans.