As many developers have pointed out right now the iPhone burns most of the cpu cycles for the watch apps, cpu and processing = a battery hit. Native apps means more responsive apps Watch apps which means that we use the apps more. It's no secret that we will see lower battery life on the watches. The question is how much? Native apps Will rock! It's not all roses though, along with battery life also remember that every time you need to query the Internet/load data for the app you will need to go through the Bluetooth connection and that will give us the familiar "wait wheel" we all love. So what I'm saying is temper your expectations. It will be great, but at a cost.