I have never used whitestrips of any kind before, and was looking for an inexpensive yet effective way to whiten my teeth. Keep in mind, I have pretty severely stained teeth due to heredity, coffee drinking, and inability to afford dental care for the past 10 years. I didn't expect dramatic results whatsoever, but these produced NO results when used as directed. I did experience mild/moderate sensitivity, but that came and went during the 15 days I used this product and was not enough to cause me to stop/pause using the product. The strips do slip around, but I didn't think it was as bad as most of the reviews make it out to be. You definitely cannot eat/talk with these on. The label says you can drink water, but I disagree. I plan to wait a few months and then try the Crest Intensive Professional Effects.