This strap is designed to offer a hands-free drinking experience. However, a metal water bottle slamming against your hip as you walk may not be ideal.
This snack ring is impractical for almost every application, like going for a walk or sitting on the couch. It would only be useful for driving or road trips.
A good idea in theory, the practicality of attaching a flimsy piece of plastic to another piece of plastic is flawed. The attachment may scratch your Stanley.
The neoprene coating supposedly prevents the cup from chipping when dropped and costs about $10, which is a bit much for a cup that's already insulated.