The success of the FitBit Force wristband in the nation’s market remains to be seen as the device is drawing mixed reviews despite soaring sales in the U.S.

According to recent data by NPD Group, FitBit accounted for 67 percent of units sold in the activity-tracking category last year in the U.S., outpacing sales of its rivals including Nike’s Fuelband.

The smart device takes the form of a wristband, and keeps track of sleep patterns, the minutes a person is “active,” calorie intake, and the number of floors climbed and steps taken.

The wearable device motivates people to exercise by also setting personal alarms for goals accomplished for the day and the amount of exercise left to reach the set target. Realtime status can be checked online and on other smart devices through the FitBit app.

Matthew Moskovciak of Cnet, however, wrote that the M7 motion coprocessor chip embedded in his iPhone 5S has replaced his FitBit wristband.

The FitBit wristband has no display and the activity tracking feedback is available on a smartphone interface, something that is no different than using the same chip in a smartphone. Using himself as an example, Moskovciak points out that users will stop carrying an extra device as it is replaceable by the internal chip in smartphones.

He urged the company to focus more on software in the future, explaining though he probably won’t buy another FitBit activity tracker, he will continue to use the software it provides on smartphones.

By Yoon Ha-youn, Intern reporter (yhayoun@heraldcorp.com)