We've enjoyed Rainforest Cafe on two different trips, but both times we went around late lunch (1pm), both times with reservations made a week in advance just in case. The food (at least what we had) is a little above basic, neither slop nor fine dining, but priced up a bit from the norm because you're paying for the jungle atmosphere. Garden-burger was good, salad very good, fries okay, mac'n'cheese generic. Expect a minimum of about $12-15 per person.
The Restaurant (in DTD) was about 30% full one trip and 75% the next, and was definitely much louder as it got fuller. I personally would not go at night when it nears capacity, as it could be deafening in the sections near the animatronics. I don't see how any waiter can do it without ear protection. I would guess that it is maybe not as loud in the lower section near the restrooms.
Waiters were efficient both times.
Definitely a fun place for kids, but can scare 3yo and under if too close to "elephants."
We will eat lunch there again on our next trip.