We went for the first time last spring with DS7 and DS15. I'll echo what everyone else has said about making ADRs as soon as you can. It seems like a lot of trouble now, but is definitely worth it when you get there. We used all of our TS credits on dinners and paid OOP for character breakfasts at Ohana (Lilo & Stitch) and Crystal Palace (Pooh characters). Both were great.
We also enjoyed:
Le Cellier at Epcot for dinner (TS) - best meal of the trip
Hoop de Doo Review at Fort Wilderness (2 TS credits, but worth it for us)
Fantasmic dinner package at Hollywood & Vine at MGM (1 TS credit, buffet) - pretty good food when we were there and great seats for Fantasmic
Flame Tree at Animal Kingdom (CS - with large servings)
Pecos Bills at Magic Kingdom (CS)
We ate at Biergarten, too, in Epcot and while everyone enjoyed the atmosphere, the boys weren't too impressed with the food.
One big thing to keep in mind: If you're not park-hopping and make a reservation for a restaurant at one of the parks, it has to be the park you're in that day or you won't be able to get in for dinner.
Park-hopping helps with that, but you still dont' want to be running all over the place for dinner so try to map out where you think you'll be each day and then make your reservations asap. You can take advantage of nearby resort dining if you're not hopping and return to the same park later. That's what we're doing on a short trip in December.