The short short version: the buffet is overpriced but pretty ok; the service is lax; and (spot the pet peeve) they have the annoying “policy” of not seating your party until everyone is there. This is fairly annoying when six of seven people are there, the other one parking the car in the overstuffed clocktower lot, and the one space available for all of us is severed into two four-tops ....
The food: the spinach pakora was OK, a bit greasy; the aloo parantha were very good, nicely hot & fresh from the oven; the halwi was not sweet enough, and had only the very occassional sliver of almond or sultana (it was more like cream of wheat breakfast than an Indian dessert); no beverage other than water was offered.
If you =must= have Indian in Herndon, this is probably your best choice.
But I suggest you either drive to Connaught Place or go next door to Sorrento for decent “Mediterranean” food.