This is a review for the Crest 3D Glamorous White toothpaste, different from the Vivid White toothpaste in that it claims to remove 90% of stains in 5 days (as opposed to 80% in 14 days). It also claims to noticeably brighten your teeth in just 1 day.
My teeth are not SUPER discolored, but since I drink coffee and tea regularly they are a little yellow and dull looking. I wasn't really expecting it to work, since I've used whitening toothpastes intermittently in the past without any noticeable effect. I didn't notice any change in the brightness of my teeth after the first day, so I figured it was another dud. I kept using it though, since I needed toothpaste. I've been brushing with it 1-2 times a day for about 3 minutes, for about a week. Last night I looked closer in the mirror in surprise, because...results! I'd guess my teeth are maybe 2 shades whiter.
It's worth keeping in mind that this toothpaste whitens via polishing stains from the surface of your teeth with abrasive silica, not by using bleaching chemicals, so if the color of your teeth are naturally more yellow-toned then this might not work as well for you.
It also won't really give you a blindingly white movie-star smile, since that level of whiteness can only be achieved with bleaching or veneers. What it does give (or at least gave me) is nicely natural looking white(r) teeth.
Overall my experience with this was nice--the packaging is good, it comes in a plastic tube which makes it easier to squeeze the toothpaste out (unlike metal tubes), and the cap is big and has a large lip which makes it easy to open. The taste is an unoffensive mint. It's slightly pricey if you buy it in stores (I bought mine from Duane Reade, and it was one of the more expensive toothpastes at $6 for 4.1 oz) but you can get it much more cheaply online from Amazon or Drugstore.com.