Far from religiously observant, Singh is overweight, fond of beer, curry and smoking, and wears white trainers everywhere. He is not approved of either by his wife, who is in the "she who must be obeyed" tradition, or his superiors, who don't think he fits into the culture of the force and try to keep him out of the country. Singh is something of a caricature, who doesn't really develop as a character between books, but he's an original and engaging one.
The plots involve prominent topics and high politics: in Malaysia, ethnic divides and the role of shariah family law; in Bali, a terrorist conspiracy, tourists and expatriates and Javanese migrant workers; in Singapore, a partnership of high-flying lawyers; in Cambodia, the work of the tribunal trying Khmer Rouge war crimes; in India, industrial pollution and communal conflict; and in China corruption, property development, and the suppression of falun gong. These settings are handled nicely, with no artificial information dumps, and if they sometimes follow fairly stereotypical lines that's unavoidable in an incidental presentation that has to be accessible to general readers.
What makes these novels a success, however, are their individual stories. These are entertaining and well-paced, with a bit of suspense and some surprises, and they have a good cast of characters — in almost all of them families and family connections play key roles. And Flint may not have literary pretensions, but she writes straightforward and effective prose.
There is no real progression between the novels, so they can be read in any order. If anything the later ones are better, so there might even be an argument for working backwards.