I am going to say yes... from what I have read alot of the resort people will eat at this resturant so that when they arrive at the parks they can go,go,go,go. ADR is recommended for sure. We are staying at POR and have adr's at the resturant four times during our 12 day trip.
We stayed at POR and ate breakfast there twice without an ADR. One time we waited about 3 minutes for a table (which I didn't understand because there were tons of empty tables) and the other time we walked straight to our table. We decided to go there the second time because the food court was packed. We probably finished our meal at the same time as the diners at the food court who arrived at the same time we did!
Make sure you get the stuffed banana french toast. It's awesome!