It depends on you and the ship your on. We went on the Allure last and got the Unlimited dining for $175 a person. For us, it was worth it. We loved the restaurants, especially chops. We ate in the MDR one night, and it was horrible. Could've been just a one off or a bad night for them.
I agree with try it once and see. You could even just get the chops + 1 dining or the 3 night dining to try it out.
Not sure what others opinions are on the MDR on Allure/Symphony/etc.