The 2015 Mobile World Congress has just finished. No matter whether you are a tech guru, I believe you will pay attention to the high-end mobile phones revealed by the giant vendors, like iPhone 6S/7, Samsung Galaxy S6 Edge, HTC One M9, Sony Xperia Z4 and so on. In front of these fabulous gadgets, which one impresses you most ? Would you upgrade your phone for the new one?