Hard to say, as I've never had a smartphone so I don't really know what the difference would be. But I will say that I see a lot of people walking down the street with a phone to their nose, so... I'm probably seeing a lot of stuff they don't. :-)

The closest comparable thing is that I've gotten kind of hooked on listening to podcasts while doing chores. It's highly addictive and now I feel uncomfortable doing without. But when I do eschew the podcasts, I end up doing a lot of processing of my own thoughts that's probably pretty valuable. Kind of like shower thoughts, I guess.