I use this mouthwash twice a day - in the morning after brushing, and last thing at night - and I saw a slight increase in whiteness after a week. I'm not talking Cowell dayglo white, but there is slightly more then there was with my previous brand.
It doesn't taste bad, vaguely minty, but there is a slightly odd aftertaste. It didn't put me of continuing to use the mouthwash, as it does feel fresher for longer than my usual brand [Colgate] makes my mouth feel.
So would I use it again? In all honestly I'm not sure; the product does do what it says it will do and those results are noticeable quickly, but the price does make me hesitate, as the results aren't amazing to me.