The sipping lid leaks and the other lid isn't useful for my use case. Also, it'd be great if Ember can figure out how to both charge the Tumbler and warm coffee at the same time. Even though I can't take the Tumbler out on the go due to the lid leaking, I do like drinking decaf coffee all day long where I'm not always at my desk. It'd be great if I can quickly charge the Tumbler while coffee's in it before walking away from my desk again.