I guess my wife and I fall within the category of the "American" "White people" whom Zack F. disparages in his review, but we eat a lot of Indian food and we think Marigold Mansion is excellent. We had the Lamb Saag and the Chicken Tikka Masala (which incidentally is not an Indian dish but one allegedly created in Scotland of all places!!), and they were excellent. Each of them had a very slightly different taste (the Masala had a nice light sweetness and the Saag had a real taste of spinach), but we really liked them.
We prefer food that is flavorful rather than just fiery hot, and Marigold Maison's mild version was perfect. You could taste the flavors while still getting some kick to keep it interesting.
I agree with some of the other commentators that the prices seem slightly higher than some others, particularly given the non-fancy ambiance, but the portions are very generous. We had plenty to take home and enjoy the next day.
Also, the staff was friendly and attentive (although we were there on a night that wasn't very busy due to the rain - yes it rains in Phoenix). We liked it enough to buy a gift certificate, so we will be going back.