The cuisine there is truely authentic and is rarely found in other parts of Hong Kong. The owners there are really of South Asian descent and offer the food at exceptional prices. A sample shop I went to had an excellent variety of food (and portions) especially pathiri, hummus and curry.
However, the building has come under serious controversy due to public safety inside the mansion. Its age is beginning to show as well as a slack management system (though they have recently installed CCTV cameras) and regular blockage of emergency exits. It is also known to be a centre of drugs, and a hangout for criminals and illegal immigrants. Nonetheless, police have conducted frequent checks and raids to prevent such activity from forming and the situation has improved considerably.
Hopefully, you won't be scared off by the above and relatively dim environment. Just think about all the good stuff you'll be able to try.