I highly recommend the CRT lunch. The salmon with asparagus and crab risotto is the BEST meal I've had anywhere on the Disney property.
We went with a group of 14 in October 2005 and everyone loved the service, the food, and just the cool ambiance of eating in the castle. They still have the same choices for lunch that they had last year, and the blueberry buckle dessert is awesome!!
I don't think it's worth 2 TS credits, but with the DDE discount, the cost is probably worth paying OOP.