One has to pick the time, conditions, and place carefully.
It helps if one has been barefooting over various surfaces to
toughen up the soles of one's feet beforehand. I once made
the mistake of going on a hike where the trail started out fine
with smooth, damp, packed earth. After a few miles, it turned
into large gravel, with prickly nettle-like groundcover along the
side of the trail. Large gravel can be very tough on the feet!
It took me about three times as long to finish the hike! So unless
one already knows the route or has talked to someone who has
hiked it barefoot, caution is in order when hiking over an unknown
trail. I know it may sound like heresy to hard-core barefoot hikers
(and there are many, believe me, for whom bringing along
flip-flops would be near sacrilege), but it seems to me like misplaced
martyrdom to endure needless suffering just to prove a point,
one's fearlessness, machismo, or other such "priority." Barefoot walking
and/or hiking should be enjoyable. When it ever becomes like a
miniature torture, it is time to desist and rethink what one is doing.

I use to alwasy run around the farm barefoot I still take walks etc...places you get strange looks from people but I think it is wonderful . There is even a club for barefoot runners.

I've been barefoot hiking as long as I've been barefooting. I'm one of the founding members of the Barefoot Hikers of Minnesota ("Soles in touch with nature"), and we get together for monthly hikes around the state. You're right: it's like opening up a whole new set of senses. You experience your environment as you never had.

As Loren mentioned, trail surfaces can be unpredictable. Bringing along a pair of flips is a good idea in case you run into a stretch of gravel or something that you can't handle. It's not worth damaging your feet.

Happy hiking!