Data from multiple sources, compiled by Seeking Alpha's J. M. Manness, indicates that in the winter quarter Apple sold 31.9 million iPhone 5s units, 12.8 million iPhone 5c units, and 6.4 million iPhone 4S units. That is a ratio of about 2.5:1 for iPhone 5s:iPhone 5c sales. Clearly the iPhone 5s is the preferred device; however, lets compare that to the competition.
The iPhone 5c over doubled BlackBerry's total smartphone sales of 6 million for the quarter. It easily beat sales of 8.2 million Nokia Windows Phone devices which account for a nearly all Windows Phone sales globally.
The iPhone 5c also beat out Samsung's flagship Galaxy S4 which sold an reported 9 million units in the winter and LG's flagship G2 which sold 2.3 million units in the quarter.
As you can see in the charts below, the iPhone 5c was in the top three devices for each U.S. carrier, consistently topping every other device but the Samsung Galaxy S4.
While the iPhone 5c may have not performed as well as expected, it certainly didn't 'flop'.