My dental hygenist recommended getting a Waterpik. The water pressure was more than I expected even on the first setting. After only a few weeks I am getting used to the pressure and see a difference in my gum health. The "on" switch is very difficult to move with one hand. Perhaps it'll get easier as the button "loosens"? Generally, very pleased with it.
As a recommendation from my dentist, I purchased this and have been using it for a couple of weeks. If you're teeth are all evenly spaced, then regular flossing is adequate, if not, this really helps. I wouldn't recommend doing this in public.