Try searching the review board. There are several Nick Hotel reviews which include reviews of the breakfast. Most say it's not worth the extra money. If you eat the regular buffet, kids eat free, so it's only $20. Kids are not free for the character meal, there are only a few differences between the offerings at the buffet (character meal has made-to-order omelets and waffles), and the characters are plentiful in the mall from 1-3 pm.
I read tons of Nick Hotel reviews in the last week, and that's my memory, at least.