Review (1/5): Would not recommend for whitening
After several uses, I didn't really see a difference.
Update May 2016: I have tried using this product in several ways; once weekly, twice weekly, every other day, only at night, only in the morning...even as a face mask (haha, DO NOT try that one). Not only did it NOT whiten my teeth, it leaves a huge mess and takes forever to rinse away from both mouth and sink.
The only positive thing I have to say about the product? My kids thought my blackened mouth was hilarious.