Apple released iOS 7.1 beta 3 to developers on January 7 and with it a revamped Phone app. As you can see by these screenshots, courtesy of iClarified, Apple has changed many of the rectangular bars found in iOS 7.0.x (left) to round buttons in iOS 7.1 (right):

 

 

In addition to the changes in the Phone app, Apple has toned down some iOS 7 elements that gave some users motion sickeness (including vertigo and dizzyness) with slightly darker Phone, Messages, and FaceTime icons, a new option to reduce iOS 7’s white point (found in Accessibility’s Contrast menu) which joins both the “Button Shapes” and Darken Colors options that were added in an older iOS 7.1 beta, and a new option to turn parallax on or off when setting wallpapers. A report from BGR, and a spate of remaining bugs, suggest that iOS 7.1 probably won’t be released until March.
Source : ZDnet