If you are using a smart phone to be more productive and to help make the work you do better, then all right.
If you are using a smart phone just because it's the latest gadget, no good.
I was told that Amish people don't use phones just because they don't want technology. It is partly because they have a religious requirement to remain separate from "English" society but it's also because they believe that, if you want to talk to your neighbor, it is better to get your lazy butt off the sofa, walk down the road and knock on your friend's door. The Amish place a high value on face-to-face contact and personal interaction. Not a bad value to have, really.