The positives: the bottle does exactly what it claims to do & keep drinks cool, as long as you make sure it is properly closed - I realised this after leaving the bottle in my car on a hot day and finding my cold water was actually warm, due to not having tightened the cap properly. (I haven't yet tried hot drinks in it, so can't comment on whether it keeps them hot) The not-so-positives: size-wise, I bought the 500ml bottle which is a lot taller and slimmer than it looked the pictures, and doesn't sit well in my car drinks holder. I also find the lid fiddly to use - it takes a lot of unscrewing, but this is probably how and why it keeps drinks at the right temperature regardless of outside temperature. All in all, a reasonable purchase, but not quite living up to the hype!