This is the best whitening product I've ever used. No tricky molding of mouth trays, no hours of downtime with trays in your mouth over the course of a week or more, and no more burned gums or tooth pain. It only takes a few minutes, twice a day, to conveniently and painlessly whiten your teeth. I even used this on my 12 year old daughter's teeth over one weekend and, come Monday, several of her friends commented on how bright her smile was. One girl told her, "Wow, you've really been brushing!" -- my daughter just smiled ;) She's at the age where she's getting very conscious about her appearance and this product really gave her a confidence boost. (Please note that it's not recommended for children under 12.)
We saw noticeable whitening from the very first application. A reviewer at another site wrote that this product was not effective at all, but I believe that may have been because directions were not followed carefully -- we were super pleased with the results we saw. Make sure to use the recommended amount of accelerating rinse, then immediately proceed to the second step. Remember to shake the whitener before applying, and be careful not get it on the gums. Do let it set for 30 seconds free from contact with lips or tongue. One thing I found very useful was to put a roll of gauze between the lip and gums to help keep teeth clear when applying the whitener and while waiting for it to set. Also, make sure not to drink or eat anything for at least 10 minutes after each treatment, as directed.
As far as effectiveness and value, I'm very satisfied with both. We had enough for the full, three-day treatment, plus a few touch-ups per package. You don't need to apply the whitener heavily; we just brushed on a very thin layer and we noticed the whitening effect with each application. There may be stronger whiteners out there, but they are no way worth the pain they can cause to teeth and gums - especially where my daughter is concerned. I'm so glad I found this product; it definitely earned five stars from me.