I went to school in both places, and as someone pointed previously, it all depends on the individual person and the specific schools attended. In the DR, an education can vary greatly between schools, particularly when comparing public to private schools. I think that the same can be said for college level education, as I have spoken to many friends and relatives that have attended college there, and it is obvious that the quality of the education differs from one institution to the next.
However, I'm a strong believer that an individual and his/her attitude toward education greatly impact the end result in any case, whether they are educated in the DR or the US. If you go to any high school in the US and look at the next graduating class, you will find that there are students who will graduate having completed a college level calculus class, while there are others who will graduate having only completed a basic algebra class. The difference is a student pushing to be the best, while the other is pushing to just get by.