Bests & Worsts Reviews from Amazon

The bottle is mostly pretty good, but it leaks when you shake it. Considering that shaking the bottle is part of it's intended us, it shouldn't leak, even a little. Gentle shaking isn't an issue, but vigorous shaking to blend in powders will cause leaking. You definitely don't want to put this in your bag on it's side, it will leak. Besides the leaking, the bottle looks great, and is well insulated. You can make a shake with milk and not worry about it warming up too quickly. If the bottle wasn't purpose built for shaking, I wouldn't be so hard on it, but considering it is built with the sole purpose of being shaken, it should seal well enough to avoid all leakage.