I have been to frank once for brunch, and did a full course brunch.
Pastry basket, two appetizers and two main dishes ( I was with a friend).
Everything (minus the typo on the Menu, which oddly hadn't been fixed, considering the place has been open several months...) was pretty delicious, except for my main dish.. the pancakes were not what i'd say were.. delicious.
The hostess was nice (granted I knew her from university) and our server treated us well. He was there when we needed him.
The goats butter with the pastries is amazing!
In the end, my friend had a great breakfast, and mine was great until the main dish.
All in all for two people to brunch it cost us around $80, without alcohol.
To recap:
Good food (if you choose better than me)
Expensive (either for the rich, or a once in a while)
Great start if you plan to go to the AGO after