The iPhone 6S had a mostly positive reception. While performance and camera quality were praised by most reviewers, the addition of 3D Touch was liked by one critic for the potential of entirely new interface interactions, but disliked by another critic for not providing users with an expected intuitive response before actually using the feature. The battery life was criticized, and one reviewer asserted that the phone’s camera was not significantly better than the rest of the industry. The iPhone 6S set a new first-weekend sales record, selling 13 million models, up from 10 million for the iPhone 6 in the previous year. However, Apple saw its first-ever quarterly year-over-year decline in iPhone sales in the months after the launch, credited to a saturated smartphone market in Apple’s biggest countries and a lack of iPhone purchases in developing countries.