I have one of these and two in the 21 oz version. so far so good. they do keep your water/gatorade cool but only for about an hour or so in 95 degree weather; oh well, what can you do?
the valve lock feature has saved me from messing up by front teeth and having to visit the orthodontist.
also, i've had these for about three months and haven't had to wash them in the dishwasher; they have maintained a funk-free taste. I have used them for water, gatorade, and Skratch Labs.