According to a report from the NPD, Disney sold 551,000 of those units (which cost around $75 each) in the month of December alone. By comparison, Activision's newest Skylanders product, which also uses a base for which you can buy toys separately, Skylanders SWAP Force, sold 597,000 units since it launched in mid-November.
President of Disney Interactive James Pitaro told the Times that sales have greatly exceeded the company's internal expectations. “We’re thrilled that families and gamers alike have embraced Disney Infinity,” he said. “We believe we’ve set the stage for Infinity to be an enduring video game platform.”
As we learned from Disney's last earnings call, Disney Infinity significantly helped the struggling Disney Interactive, which swung from a loss of $76 million in the last quarter to an income of $16 million.