Instruct: Classify Amazon reviews into positive or negative sentiment
Query: much better than I expected

I read a lot of bad reviews about this product before I bought it. I had been using Crest whitestrips but they just were not doing the job, so I figured I'd try my luck with the Aquafresh trays despite the poor reviews. I must say I am pleasantly surprised. I experienced absolutely none of the uncomfortable effects that others reported, and I am shocked at how white my teeth got after even the first use. I have a feeling that because I have used many whiteners over the years (including custom dental trays from my dentist before over the counter whiteners became popular)my teeth and gums are less sensitive than most people's. I would definitely recommend the Aquafresh trays, but perhaps not for a first timer. I think you should probably work your way up to them, maybe by using whitestrips first. The only reason I did not give them five stars is that a couple of the bottom trays did not fit as well as the tops.