On one hand, you've got to sympathize with Boori Ma. She's a refugee in Calcutta who lives on the open rooftop of a lower/middle-class apartment building. Her "job" is to guard the building and keep it clean; in return, she gets an occasional free cup of tea, some social contact with the residents, and those cushy quarters on the roof.
Plus, she gets thrown out of the building for something she didn't have any part in (the theft of the building's only sink). In other words, Boori Ma's a character to pity.
She's not a completely likable character, though. She loves to tell stories about her past, stories that—if we're honest—are probably mostly fantasies and lies. As Mr. Chatterjee—one of the residents—likes to say: "Boori Ma's mouth is full of ashes" (IM 74).
In fact, she likes to complain a lot, with a voice "brittle with sorrows, as tart as curds, and shrill enough to grate meat from a coconut" (IM 2). Maybe not the kind of person you would want hanging around your place even if you do feel sorry for her.