The slide is VERY slick now, especially compared to when it was pitted and weather-beaten. I've been a slacker on getting the water lines plumbed properly to the slide again so right now the only way to get water on the slide is to spray with a water gun from the pool or hose. My son goes down all the time with just his wet trunks on and it is plenty slick. My daughters go down as well, as long as the slide has been sprayed or my son has just gone down. 
Even hands-first...
Even hands-first...