In this particular application I am installing it where I previously had a GE (Jasco) Z-wave switch which is much bigger. The GE switch does handle more load, but for most locations 600/150W would be sufficient. Even though this unit comes with short pigtails that take up additional room in your gang box, the flexible wires make stuffing the box easy. The flexible wires and smaller size means you're less likely to need to replace your box like I had to in some locations with the GE units. Another great feature of this device is that it automatically can switch between line and load. So unlike the GE switches that require you to know which black wire is which, this device doesn't care. Like the newer GE switches you do need to tie it in to your neutral wire. This allows the devices to always be powered regardless of switch state.
After installation you simply press the bottom button to make sure you have control over the light and you should be greeted by an orange status light. Then if you don't already have the ecobee app you download it from your respective store and simply follow the prompts. Below are some screen shots of the install. You start by selecting the menu then Add/Install Device.
After this you will get a few more prompts to finish the configuration of the device to use Alexa and to control the Smart Features. First you will get a chance to link your existing Amazon Alexa account. Then you can configure the Smart Features; in this case I initially set all of them to be enabled. But your choices are auto shutoff in an empty room, auto on when dark, auto on when someone enters, and a nightlight for when it is dark.