This is another of those books that's left me in two minds. There's no doubt that Desai has a talent for evoking setting - while I've never been to India, her version of it felt real and was fully, almost tangibly realised - and her characters are believable and lively. Moreover, her themes are interesting, and interestingly developed - the major threads are the tradition/progress tension (as played out in the decline of Urdu/Nur, the under-funding of the humanities, the attempts to mechanically record Nur's recitals, and so on) and the importance of literature, but there are other, often related strands (the role of the family and the position of women in society, particularly in India, and the nature of life as an academic, come to mind).
I think that, to a pretty large extent, Desai intended these themes to crystallise - and, in the case of the tradition v progress theme, to reach a kind of partial resolution - in the final chapter, and consequently a great deal hinged on that final chapter, and particularly on the closing few paragraphs. Unfortunately, however, the closing didn't entirely convince me. I felt that Desai hadn't really 'earned' the right to end in the way she did - Deven's closing thoughts didn't strike me as either consistent with, or natural developments from, his thoughts and actions throughout - leaving the novel as a whole somewhat uneasily poised.
As a result, while I thought that In Custody was a good novel, it didn't really touch me deeply. Still, I'm glad I read it (it was actually a gift, which of course makes it more valuable) and would be interested to check out some more of Desai's work in the future.