If you'se using xoom to send money to a USD$ account in DR, then it's good. If you send it to a pesos account, the exchange rate is low and they charge more. I use my credit card because I don't trust them with my bank account. Western Union is the same thing. On the other hand, a transaction with xoom is completed within a day.
I ended up opening up two savings account in the same bank, with both having an atm card. I just transfer the money to her account and she retrieves it using her atm card. It's been the easiest way so far.