I bought my first one maybe 6 years ago, back when they had lifetime guarantees. I've never tried to return them after they break because they were cheap enough that their cost didn't justify the time expense necessary to go through with the process. I've used mine for the gym and work. I've since gone through 3 more (including one of the 500ml ones) and noticed that they don't have lifetime guarantees anymore! I would say they last about 1-2 years. Not bad for seven bucks. Even in the heat, the water is as tasteless as a Nalgene bottle (which would be the less convenient more durable competitor). However, the light weight and malleability let it fold into your bag MUCH easier, which is why I keep coming back. When it breaks, it will be by the spout - it will just leak one day where the hard plastic meets the bag...hopefully not on anything important (don't get too comfortable sticking it in your laptop bag). 4 stars

As an international flight attendant I take this on all my flights.
I have had one of these for about 10 or plus years. I have used it heavily. It is worn out now, and I am ready for another one.

Travel tip:
If you are cold at the hotel you can fill it with hot water for your bed. Just wrap a towel around it if it is too hot.
This thing is sweet. 5 stars

I ordered theses collapsible water bottles for a trip to Disneyworld. They did a great job meeting my need for a light weight container to carry in my bag. I would fill them at water fountains, add one of those powder packets and instantly I had a refreshing drink to keep me going. The only challenge was getting the bottle to stay open enough to begin filling. Once enough water is in though, the bottles fill nicely and are easy to hold. 4 stars

This is certainly a cool and attention-getting water bottle. Be aware that the two-liter size is very large and probably too big for every day use. Because it is not rigid, you need two hands to drink from it (or spill it all over yourself.) Can be frozen. 3 stars

Its really convenient and I even got compliments about how nice it was. They are made of very light material but I haven't had any problems with leaking. 5 stars