It is, but it's different from lunch. Dinner is a character meal and the menu is limited. If you haven't already, you should take a look online at the menus for lunch and dinner.
Yes lunch and dinner can be used with the ddp. I've had lunch there twice and dinner there three times. Service was great and character interaction (dinner only) was great. I really liked the pasta for lunch. The food is served family style for dinner and everything is delicious!
...dinner is served family style. Liberty tree is totally overlooked by most...but, it's one of our fav's....and on our list this trip...and it is on Disney's DDP...!!!