I've only been to the Rainforest Cafe once, but I wasn't very pleased overall. I was there around 9pm for dinner during the first few days of December, but we still had to wait a good 30 minutes for a table. (That'll teach me to make reservations.) The server was unpleasant and acted as though he was mad at someone he worked with. The meal I had was bland and was something most people could probably make themselves in a matter of 10-15 minutes. The experience as a whole made me feel like I was at a chain restaurant (which I know it is) at another resort all together. I'm not too sure why people love this place so much.
I feel kind of bad for posting this because I don't think I've ever had a bad experience at a WDW restaurant before, but I just thought I'd give my opinion. It just didn't feel like a Disney experience.