I definitely agree with Mike's recommendation to start out the climb with a group. It's best to get as close to the guide as possible within the chain. The guides don't waste a lot of time once they start the climb, but invariably somebody breaks the chain.
The purpose of the chain is to help one another where you get to big steps or a rock that might be exceptionally slippery. One person does the step, and with the two persons in front and behind providing stability, then turns to assist the next person.
If you decide to "punt" and go on your own, you do so at your own risk. I don't recommend it if you don't know the falls.
The water is splendid and crystal clear, just as you would expect of a mountain stream. I did not find it to be particularly cold, though it's cooler than the ocean because the falls are well shaded.
Have a great time!