I've used this product almost every day during the last 9 months in Nepal. I've used it with tap water, river water, water from tanks. I'm yet to get sick from drinking that water. My house doesn't have a water filter, so using this bottle to take water to work saves me having to waste gas by boiling water. I recently took it to some remote villages, where it was over 30 degrees C and we were walking for 6 hours a day. I was able to fill up at any water tap along the way, and didn't have to worry about getting sick.
My only problem with this bottle is that it leaks slightly out of a hole on the top (underneath the flip spout), which means that if the bottle is ever on it's side in a bag, the entire contents become wet.
It's fairly easy to clean by removing the filter, with the only problem being the spout getting easily very dusty. I sometimes feel as though I am constantly slipping bits of tissue down the spout to clean it. That said, I would recommend this to anyone, and am about to buy one for my colleague, to replace her more expensive bottle which is on it's last legs.