We've had breakfast at Donald's five times, and we've always enjoyed it. My younger DS is a huge Donald fan, which is why it's a must-do on our family trips.
The food is typical breakfast buffet fare. Every time that we've been, the buffet has been clean and well-stocked, and the food was hot and fresh.
We've had some servers that were better than others, but we've never had bad service. The better servers at Donald's play jokes on guests and are really a lot of fun. We've had two really funny servers there.
I have two sons, and they like the theming at Donald's. It's set up as the camp of an archeological digsite, with dinosaur artifacts all around - more "boyish" than the theming at other character breakfasts.
We've always had good character interaction at Donald's, and all of our favorites are there - Donald, Mickey, Goofy, and Pluto.
Donald's can be crowded and noisy, but I think that's probably true of most character meals.
The most common complaint that I've read about Donald's is that people have felt rushed through their meal and in the character interaction. This has never been our experience. We usually spend close to an hour on our meal, and we've never felt rushed to eat. And the characters spend as much time with us as they did at any other character meal we've done.