Haveli competes with the many other Indian restaurants in the Madison area. I recently enjoyed Haveli's buffet on a Sunday mid-day. My partner and I filled one table of maybe six in their large dining room. The dining room is much more beautiful and filled with light than most of their competitors (say, Swagat, Maharaja, Kangchen). Staff was fairly friendly and very attentive. Due to the small amount of diners, we never had to wait in line; this can be an issue at some competitors (primarily Swagat, though phenomenal).
Haveli's food was very good; all standards you would find at most Indian buffets were present. They provided diners with an average amount of spice. I would say this buffet is somewhat smaller than others in town. For example, there were very few condiments (i.e. chutneys, raitas, etc) and one of each food category except chicken had multiples. I guess how many items do you need? Even if it's excessive, I do prefer enough variety to have two plates full of new items (yes, my deadly sin is gluttony).