I suppose, smartphone is just another tool that humanity has crafted, similar to hammers, axes, and billions of other things we invented to make our lifes easier. It lets us interact quicklier and more efficiently, gives instant access to terabytes of information on the Internet, serves as a photo/video cam and so on. Yes, people started using it so often that its changing the whole world. But I dont think we can refer to it as addiction, its just technological progress.