We went in May (the Sunday before Memorial Day) and are going again in September. Getting a reservation for September was much harder than for May. As another poster said, brunch is only offered on Sundays so reservations may be difficult to get depending on when you want to go. I used Touring Plans to get the reservation in September.
There are 2 parts to brunch: the buffet and the table service. The buffet has things like sushi, salad, charcuterie/cheese, fruit, bagels, etc. Once you've had your fill of that, you will order your entree from the menu. There is also a bloody mary bar (at an additional cost), but mimosas, sodas and french press coffee are included. Oh, and you'll also receive a dessert platter after you finish your entrees. I'm a vegetarian, so I didn't sample any of the meat offerings, but my husband said everything he had was really good. We're really looking forward to going again in September. Be warned - you will be totally and completely stuffed when you leave, so don't plan anything too crazy for a few hours after you're finished lol!