Before i bought this, i went for a cleaning. Hygienist checked for gum pockets with millimeter tool and i ranged from three to six mm gaps (which is pretty bad indicating beginning gum disease). My gums were also bleeding pretty bad. I spent a couple hundred $ on a deep (and painful) cleaning and then bought this machine that week. I have been using it (both waterpik and sonic brush) once a day ever since with only a couple of gaps. Went to the dentist again yesterday. Gum Pockets had decreased down to mostly 1-3 with the six's down to mostly fours (a couple of fives). The same hygienist as before concluded that a normal cleaning was appropriate this time. So, in one (the next) visit to the dentist, i saved the money spent on this machine. Pretty good return on investment. (Hygienist did say that i should floss more... That this machine is not a full substitute.). Hope that helps.
UPDATE: the machine (sonic brush) had a problem on high speed while still under warranty. I called Waterpik and without any problems they are completely taking care of me (and it) WAY beyond my expectations. Outstanding customer service from Waterpik. I would buy from them again without hesitation.
I purchased the product about 1 month ago. So far it has been satisfactory for me. The only drawback is that replacement brushes are not carried by local retailers.
Love my new waterpik. My teeth feel so much cleaner than just flossing I also love my toothbrush I like the timer so I know how long to brush The waterpik was recommended by my dental hygenist because I have caps on some of my teeth and she said this was the best way to clean.