I have not read this story, Meghe Dhaka Tara, by Shaktipada Rajguru (not Tagore as stated above).
Seemingly, the film shows how characters are formed/(de)formed by extreme poverty. But in my opinion, it also shows how some people, driven by their noble nature , are prepared to make whatever sacrifice is required of them, even when they know they are being exploited by other family members. (I know of several similar situations in both eastern and western families, so it is not a cultural thing, rather a demonstration of the noble human nature. On a larger scale, when the 'family' is the whole society/country some people have risen to the challenge of sacrificing their whole life.)
Very well acted. Direction of the period.
A thought-provoking film, albeit sad.