Stagnating how? Less fancy whiz-bang shiny maybe-novelty features to entertain the tech blogs and mainstream media?
Since the iPhone arrived in 2007, phones in general have made incredible advances in mobile performance, networking/cell, form factor and screen technology. This continues today, with things like crazy-high ppi screens and 8-core processors in Android phones, to things like Touch ID and the Ax SOCs in Apple's phones.