Apple just launched the "Apple Watch User Guide". It confirms you can message and use Siri if out of Bluetooth range but on the same Wi-Fi network as your iPhone. It does not say you can do phone calls over Wi-Fi. I was hoping I leave my iPhone on the charger while roaming the house but still get phone calls on the Watch. That is a killer feature. Does anyone know for sure if calls are or are not possible over Wi-Fi?
http://help.apple.com/watch/?lang=en#/apd0443fb403
http://help.apple.com/watch/?lang=en#/apd0443fb403
If your Apple Watch and iPhone are on the same network but arent connected by Bluetooth, you can also do the following on Apple Watch without iPhone:
Send and receive messages using iMessage
Send and receive Digital Touch messages
Use Siri