NPR says that some people in India are upset about Slumdog Millionaire because it portrays the extreme poverty in the slums of Mumbai. So the movie gives an unfair negative picture of the current state of that country. None of those compliants deny that there is poverty there, or that it really is just that bad.
Now, I haven’t seen the movie, but the reviews agree on one plot point, that the main character is beaten and tortured by police because they suspect him of cheating on a game show. And I haven’t heard one complaint about that. Isn’t that more unflattering to India? Every country has appalling poverty. Not every country (I hope) accepts torture as a routine law enforcement tool.