due to proximity to my office, i have tried this place once.
the only reason tiffin didnt get one star is that they do have a fancy roti making machine. pretty dang impressive.
other than that, the food is pretty sub-average for indian food. knowing that butter chicken is the indian equivalent to sweet & sour chicken balls from chinese takeout joints, it's pretty bland here. unfortunately, i think they use the same base for a lot of their food, and it really lacks flavour/spice.
it's cheap. which is why it's busy. for something actually authentic (according to all my indian colleagues), you're better off trying babakhadaba (sp?) on 17th.