Precious, in any case, is a word with two meanings, which both might apply to “The Darjeeling Limited.” This shaggy-dog road trip, in which three semi-estranged brothers travel by rail across India, is unstintingly fussy, vain and self-regarding. But it is also a treasure: an odd, flawed, but nonetheless beautifully handmade object as apt to win affection as to provoke annoyance. You might say that it has sentimental value.