Spent a total of 6 hours hiking and made it about 2 miles up the Virgin River. The water was very cold. After a while we either got used to the temperature or were numb we no longer felt it - not sure which.
Grab a hiking stick on your way into the river - there are plenty at the trailhead.
We wore watershoes we bought at Costco. These worked pretty well be we did end up with a few blisters. I'm not sure our shoes were designed for 6 hours use at one time. Rookie mistake (although my husband and I aren't rookies - we've hiked the Narrows a few times now)
Start early, before the crowd. We left the lodget at 7:00. By the time we headed out of the river at 1:30 the place was packed.