I cannot even count the number of times I have eaten at Coral Reef. It's always on the list when we take first timers (I've been there twice this year alone). Out of every place I've eaten at WDW, I think this place is more hit and miss than most. Some of the dishes here are good and some are terrible. It's generally very noisy here and they are often behind in seating and service is known to be slow. People are impatient, want to get in and out, and this is the wrong place to eat if that's important to you.
Personally, I think the mahi mahi is pretty good but have not been blown away by any of the other things I've eaten here. But it's not fine dining, it's an amusement park restaurant. I think the food is fine for what it is. The noise, however, can be brutal here, depending on when you go and the makeup of your fellow diners. Our last time there this year was awful. There are people who think it's fine that everyone should listen to their screaming children and that its cute to let their kids bother the diners up by the tank. So on a slow service day when the noise level is high, it can be painful to dine here.
But I'll be there again in 2 months, taking my 3 year old grandson for his first time to dine there.