I have heard ok reviews of there, but not really for breakfast. No matter where you go it's sort of the luck of the draw by day.
My son has a longer list than that, but basically HWV offered no substitutes for anything during breakfast. So if you look over the menu and it wouldn't work, that was it. The chef told us the sausage with cheese in it was safe for a dairy allergy and proceeded to serve my soy allergic son Van's waffles- because "it's only soy flour and that's ok." He had exactly bacon and orange juice, then developed hives and was sick later in the day.
We complained and I believe they do better now, but still only work with the main items during breakfast. Depending on your comfort level all breads and pastries may be out, you may be left with meat (likely just bacon), fruit and eggs. For in-park buffets I would really recommend lunch or dinner because they will have more ingredients they are working with. For a breakfast buffet they have more options at resorts or at Tusker house.