i haven't done the princess breakfast but I can comment on our experience on ICS
I read mixed reviews on this and thought "how can it possibly be a bad experience?" Well -- I think we experienced what some consider "bad"
We arrived at the rest. and didn't wait at all with our PS. We were sat and realized there was only maybe 2-3 other tables with people. Service was very prompt and our ice cream arrived quickly and was delicious. We were also served water in a souveneir EPCOT cup with lid/straw. (This was the only time I thought the water was yucky) The sundae were "presented" and included chocolate drizzlings on the plate and hidden choc. pieces - but all and all we were disappointed. Characters included Mickey, Minnie, Chip and Dale and Pluto (dressed in farm attire). When they did come by there interacted very well with our children; but they didn't come by much. In fact when the server stopped to ask how things were I made a point to tell him we needed more character appearance. That did bring results, but by then the "magic" was spoiled.
In short - the ICS is a nice ice cream break - I wouldn't recommend counting on it as your character "meal" as the lack of guests made for a very "blah" atmosphere and lack of excitement and magic from the characters. We went during the value season - maybe it's better on more crowded days.