My background: I drink alot of coffee, tea, and soda. So my teeth is quiet yellow. I've been using the Crest 3D white strips and didn't get the results I was looking for.
I've only used this product 2 applications and wow. What a difference it has made to my teeth they look about 2 shades whiter! Prior to this I had been using the Crest 3D white strips (professional effects) and this works alot faster! Will not be spending my $$ on Crest white strips ever again. In my opinion this actually works better. The only reason why I didn't give this a 5* is because I haven't yet used this system in the 2 weeks as stated in the instructions and also the mouthguard that comes in the kit sucks! I would reccomend getting the full kit since the pre-rinse works very well to prepare your teeth for the whitening gel. Will update once the 2 weeks is up. So far I'm very very impressed & happy with the results that I currently have.
*** UPDATE ***
The results after 2 weeks are great, Hence my change from a 4* to 5* product. A plus side to this product is that I did not experience any type of sensitivity using this compared to the crest white strips which became painful that i had to stop. I couldn't be any happier with the results. Try it you won't be disappointed.