I do this regularly when I walk around our neighborhood or to a nearby park. I usually make sure to hold the book up to help my posture, and look around frequently. Haven't ran into anyone yet, and often saw them before they looked up from their phone and saw me (most people, I've learned, don't walk on the proper side of the road). Allows me to get a lot more reading in, really, and helps me focus and digest what I'm reading a bit more when I want to.