I've been drinking a cup of coffee everyday since my sophomore year of high school. Now, five years later, it's starting to show in my teeth. I wanted to whiten my teeth just a little bit by the time I went back home for Thanksgiving, and after a week, I can really tell the difference. I took pictures before and after each use, and there was even a slight different after the first treatment. (I'm actually doing a treatment as I'm typing this up~) I'd post the pictures, but Amazon isn't letting me. :(
I whitened once everyday (usually around 5-6pm after I eat dinner) for 30 minutes. I do my lower and bottom rows separately because it was hard holding the trays in both at one time. The taste of the gel isn't too bad. Though, the next morning, I had this very dry after taste, but it went away after I used some mouthwash and drank some water.
I messed up a little on the first treatment, and got a little bit of gel on my gums. It did burn for a little while, but went away before the 30 minutes were up. I didn't feel any soreness after the treatments, so I haven't used the the blue gel all that much. I've found it easier to just apply the gel directly onto my teeth and then putting on the tray.
My only issue is the trays. I tried molding them like in the instructions, but they still didn't fit all that great. So I went out and found smaller ones and they worked fine. Another thing is that flossing after whitening was a tad bit uncomfortable. I haven't had the problem since the second treatment, so maybe flossing before-hand would be best. :)
All in all, this is a great product! I can wait to go home for Thanksgiving to show off my super bright smile to the family!
P.S. Take pictures before and after each treatment! I enjoy documenting the progression, and maybe you will too! :)