We did breakfast twice with PPO reservations a couple weeks ago.
It was worth it to us to get into the park early and to get to ride 7DMT before the rope drop crowd got there and PP before it got too busy. That allowed us to save fastpasses for other things later in the day.
We were on the dining plan, so using QS credits was fine. If we had been paying OOP, I'm not sure it would have been worth it.
As for the food, I thought it was easily the worst two meals we had at Disney. First day I got the open faced sandwich. It came out barely warm, poached eggs were hard and bacon cold. Wife and son each had the Feast a la Gaston, and the ate their bacon and potatoes, but didn't care for the sausage at all (maybe just not used to chicken sausage) and the eggs were tasteless. My daughter had the GF french toast sticks which she really liked. And for as much negative reviews as I had seen on the pastry platter, we all thought the pastries were pretty good too. So we all got our fill of food, but I'd have been ticked if I had spent $24 per person and been there for the food.
Second day was mostly the same. I switched my order to the croissant doughnut and everyone else had the same thing. The doughnut was ok, but too sweet for my taste for breakfast. Now, I kind of expected that to be the case so I'm not complaining, it is what I thought it would be. I would have loved to have that as a dessert after dinner. I ate about half of it and filled up on pastries, which was fine. Reviews of the other food was pretty much the same as the first day.
So, it was worth it to us but only because we were primarily using it for the PPO access and because we were on the dining plan. Without those two qualifiers, no way would I do breakfast there again.