(I will be stuck on an interstate bus for many hours in the near future. This may prompt re-evaluation.)
Emma Donahoe is Australian, teaching young kids English-as-a-second-language in Hong Kong. Her best gig is as a part-time nanny for the extremely adorable daughter of the extremely rich (and handsome) John Chen. The "and handsome" part is going to come up a lot, because this is a romance, no question.
The gimmick is that Chen is a mythological figure, the Black Tortoise of the North. He is stuck in human form because of plot reasons, and steadily weakening. Demons are on his case. He is trying to survive long enough for his (extremely adorable) half-human daughter to reach her majority before he vanishes in a puff of chi. Emma gets to figure this out while waltzing around with a large cast of secondary characters, including Chen's bodyguard, demons, the goddess Kwan Yin, dragons, etc, etc.
The book is good when it is showing off life in modern Hong Kong. This is a society I know practically nothing about, and it appears here in detail. (Emma spends as much time going out with her human friends as she does in Chinese-mythology-land.) It is also good when Emma, Chen, and the little girl interact as a semi-family. They all tease each other in appropriate adult and little-girl ways; it's genuinely a lot of fun.
The book is not so good when it starts rolling the romance-ball down the romance track. It's all inconsolable longings and intense angst (Emma and John cannot touch because plot reasons, except when they can). Then Emma turns out to be a natural super-hot-shot at martial arts, dismantling demons and firing off magic-chi-missiles; my eyes rolled audibly. There is some kind of supernatural explanation hinted, and I'm sure the sequels will hammer out the details, but this sort of thing does not motivate me to read them.
The supernatural stuff itself comes off rather humdrum. Not in a tantalizing "hidden depths below reality" way, but just sort of bland. I think the author has cool stuff in mind, but her style doesn't do it for me. (Insufficient reaction shown from Emma's naive point of view?) If this winds up as movies, I'd go see them.
Also, I don't know why the demons don't buy guns. Shoot the humans, take the girl. Yes, this is supposed to be martial-arts schtick, but still.
An extra-special mixed-bag point goes for Leo, the bodyguard. He is American, enormous, ugly, black, gay, and a hot-shot at martial arts (though not, of course, as awesome as Emma once she gets going). He's a great character, except the author drops in an AIDS plot thread, because -- why? Tragic gay characters with AIDS are back in style? I hope not.