I have to say I was pretty disappointed with this toothpaste as personally it didn't deliver the way I had hoped. I don't have particularly discoloured teeth but I was hoping for an obviously whiter smile and this just didn't happen. While using this toothpaste I can't say that I noticed my teeth become any whiter at all.
I'm not exactly how long I used this toothpaste for, but I went through 3 tubes of it, so that's probably a few months at least. The reason I continued to buy it was because it always seemed to be on special and I wanted to give it another chance. After 3 tubes I have given up. What I will say for it, is that it tastes really good and I have heard from friends that it has worked reasonably well for them.
I think as far as whitening toothpastes go this one didnt live up to its name unfortunately. I used up the entire tube hoping for whiter teeth but didn't notice any improvement at all. The taste is a bit strange, it was more baking soda than mint and foamed quite a lot. I wouldn't purchase it again as I believe there are much more economical versions that work better