I can't really tell you about any restaurants because we didn't really eat at any. We had most of our meals in private homes or at the Bible school. Dominican food is like that of most other Latin American and Caribbean countries: rice, beans, and plantains accompany most meals.
For breakfast we usually had bread, fruit, juice, and coffee. Lunch is always the main meal. Dominicans eat chicken, pork, and beef, when available, with rice, beans, and lots of coffee. Dinner is usually lighter than lunch but still filling. The fruit down there is much better-tasting than what we get here. They don't pump it full of chemicals, so it has the real taste. I especially enjoyed the caneppas, mangos, and pineapple.
If you will be staying in a large city, you will find more dining options, whether it be formal or casual. There are also international restaurants that serve American and Asian cuisine. If you will be staying in the country or in a smaller town, be prepared to be flexible. You will have less dining options, but will still find great food and great Dominican hospitality.
Remember, as always when traveling, don't eat or drink anything unless you are sure that it won't make you sick.