The Dining Room Upstairs is nothing like the Cafe downstairs. However, I don't think it's fair to provide reviews on any of these that have not been on the dining plan before. Going on the dining plan means that they will get reimbursed a set amount by Disney for the meals so the menus could drastically change in order for them to turn a profit. As has happened at the other signatures, most of the unique dishes will most likely fall off the menu with time.
I've dined at Upstairs, Fulton's and Portabello and have thought they were all decent enough.