Don't get me wrong, there are Merchant-Ivory films I've really loved, like "Room With A View" and "Remains of the Day." But M-I films either suck you in or they don't, and halfway through this one made me wish I had a 'relief video' handy, perhaps one with car chases and explosions.
For one thing, the title character, a thieving, scheming servant, was completely unlikable. There was no attempt to draw humor from the situation. For another, the character played by Greta Scacchi, an actress I love, was a hopeless dupe. Not only did she seem unaware of the very existence of baby bottles and wet nurses, but one would think that an upper class British woman in India would have a well-developed radar for servant politics and shenanigans.
Lastly, the film would have you believe that Cotton Mary could take a baby, ship it across the river to her sister's compound to nurse, ship it back - and still have time for her various plots? As I recall, the little buggers want to feed pretty often.
If you want to see an allegory on British colonialism in south Asia, watch "A Passage to India" or "The Man Who Would Be King," the latter having more action in any three minutes of its running time than "Cotton" had in its entire length.
