It's cool/room temperature water and feels nice.
Some people are worried about the water temperature, but it's almost always a none issue. The water sitting in the hose and the pipes in the walls of your home bring the water temperature up closer to room temperature.
See what some Whisper reviewers had to say:
"Cold water only turned out to be a non-issue. It works every bit as well as the porcelain fixtures that we once had. Excellent product!"
"Cold water shooting to a place heretofore never having water of any kind shot... I just wasn't sure. With careful control of water intensity, I of course found the worries groundless. These things are great."
"I thought the cold water would be a problem - nope! The installation is easy. I ordered a second one for our other bathroom."