To calculate the overall star rating and percentage breakdown by star, we do not use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
I've had a number of these water bottles over the years and I really like them. (The only reason I've needed new ones is because I've lost them.) I don't really use the locking feature, but I like that you can hid the mouthpiece away to keep it clean.