I love the concept of this bottle, I've always been fussy about drinking tap water and this seemed like a great cheap solution to buying bottles of water on my way to work!
My only gripe would be that I expected this to be quite a sturdy bottle, whereas in fact it feels like a plastic bottle you'd buy your milk in! It doesn't seem to me that it will last all that long - but will be useful while I have it.
Also - be very careful to rinse through the product 2 or 3 times before using it, otherwise there will be lots of black pieces of carbon floating around and coming out with your water. The bottle only says you need to do this once - so it's useful to know.
All in all, glad I brought it, but not as good as I was expecting.