I was a little on the fence about purchasing one of these as I already had an air floss device that worked relatively well. My biggest issues with the air floss have always been the tiny tank, no pressure controls, and limited usability/maneuverability. My dentist had actually recommended the waterpik to me before but had recently reiterated the statement. I have yet to use all of the included tips and settings but I have to say that it is definitely far more versatile a dental tool than anything I have ever used before. Once you get past the bulkiness of it, the semi awkward draining position required, and have honed in on the perfect pressure and tip combination, the waterpik becomes an absolutely invaluable tool for anyone's bathroom, especially if you aren't a particularly big fan of traditional floss.
P.S. There are wireless models as well but they come with less settings, less tips, and are fairly large for handheld devices.