taxis scarier than driving yourself
I just got back from the DR Sunday, and greatly enjoyed driving around the country. Even though I'm definitely neither the best nor the bravest driver, I much more preferred it over sitting in a taxi practically panic-stricken, not knowing how justified my fear is. This way at least it was up to me when to overtake or not. I must admit I got pretty good after a few days.
In the east, we had some bridge problems and had to ask around which will be the best passages. Even though travelling in a Jeepeta may have been more comfortable, our Economy Chevy Corsa was doing a great job, carrying us across small rivers, through many many hoyos, and up and down some serious hills and dirt roads.
At night, beware of the pasolas without light. Had a ugly experience a few years ago on my first trip, outside of Navarrete where we hit a driver late at night in heavy rain. Luckily the lady ended practically unharmed, I and was with Dominicans who knew how to handle the situation and I hadn't been the one driving. Still you can imagine this ended up costly and in various additional trips from the capital back to Navarrete...
Use great caution, but you will have a great time