I love this place since it's very, very, tough to find decent Indo-Chinese restaurant in the US whose flavor matches closely to the real deal back in India. I'm not an Indian, but I've tasted the real deal in Kolkata and Mumbai, and this place comes extremely close.
Walk in front of this place around lunch or dinner time and you'll see that the majority of their customers are Indians and some non-Indians who were lucky enough to have found this restaurant (usually because we're introduced by our Indian friends). That should give you the first clue of this restaurant's authenticity.
This is a typical neighborhood restaurant that caters mostly customers who live in and around Ashburn. The prices are reasonable, the servers are courteous and attentive, and the food is consistently excellent. You can tell the servers how you like your heat level (mild, medium, spicy).
Do try their hakka noodles with shrimp, or their hot fish appetizer (it beats PF Chang's hot fish any day!), or their chili paneer (both the dry and sauce versions). I found their Indo-Chinese offerings to be more authentic than the traditional Chinese offerings (such as Ma Po Tofu, which was not that good). So, I highly suggest you stick with the Indo-Chinese choices.
For dinner, if you eat early (no later than 8pm) on weekends, then you should be able to walk right in without wait. If you go late, 8.30pm or so, it tends to get crowded.