Well... they work.
I've been using Crest Whitestrips Classic for about a week now, and I was surprised that they actually work. My teeth were never incredibly discoloured, but it was enough to make me not like them anyway. In six days, I've seen a change from a light ivory to an off-white, I have no idea how bright they'll be after fourteen days, but they're certainly whitening my teeth.
The strips are a little iffy to use - it must be the way my mouth is or something, because I always end up getting part of the strip on my lip when I put them on (which means they won't go on straight anyway). Except for the first couple of days (when I definitely encountered quite a bit of saliva overload - it's gotten better), I haven't had the "drool" problem that other reviewers mentioned. I also find that the gel gets a bit... squishy after a while on my teeth, which is a little distracting, especially in the spaces in my lower teeth. I haven't noticed any real tooth sensitivity, but I've certainly noticed my gums are sensitive for about an hour or so afterwards. I also find the gel really, really gross after the strips come off - but luckily, a good brushing fixes that.
But so far, I do like the result, and I will likely try these again in the future.
