I have done a fair amount of rafting with side hikes in NRS neoprene socks, wearing them 12+ hours per day for days to weeks at a time, in hot weather or cold.
After a few days your feet will look like wrinkly prunes, unless you are careful to take care of them every night. Get out of the neoprene as soon as you can at camp, thoroughly dry your feet, and sleep in wool or (gasp) cotton socks with vaseline or some other goop to help restore them. If you don't, those prune wrinkles will dry and crack eventually, which is quite painful, almost debilitating. On one trip, we had a line outside our tent every morning of SuperGlue junkies, waiting for their skin cracks to be glued back together.
The inside of your neoprene socks will get a slimy coating of dead skin cells after a few days. Scared me the first few times I saw this, thought it was some kind of fungus growing. Just wash your socks out daily, ideally let them dry inside-out overnight, you'll be fine.
And there's nothing like putting frozen neoprene socks on in the morning. After the first couple of times, you'll learn to keep them warm at night.
I wear fingerless neoprene gloves on the river in hot weather or cold, mostly to protect my hands (see avatar photo). Like others said, their are warmer, lighter ways to keep your hands warm.