I have used this system for the past 5 years and have perfect results.  It took initially about 8 weeks before I truly noticed a difference.  Since then... EVERY time I go to the dentist I am always complimented on the whiteness of my teeth, as well as by strangers and others.  I do really like this product.  NOTE:  Your teeth can become sensitive to the "whitener" after a long period of use - just stop using for a couple weeks and your teeth will be normal again.  The toothpaste works great.  As with any new item, give it at least 90 days before you make your decision about the "whitening" effect.