ditto, my bf used them and they worked wonders. i'm going to use them soon myself, our dentist recommended the strips to us! he told us that they can make your teeth sensitive but it is never permanent. if they get sensitive, just ease off them for a day then go back to it
most of the drugstore teeth whitening products are pretty good and safe nowadays.... I wouldn't use baking soda too much b/c it is very abrasive and can harm your teeth.