I have a Motoactv. Way ahead of it's time, and it was exactly what people into fitness were looking for, with the exception maybe of lack of water-proofing.
I don't see the need for a smart watch for daily wear or use, when I carry my phone every where with me. I assume that typical smart phone owners carry their phone with them, and are able to reach in their pocket to check messages etc. and don't need the "convenience" of a watch that mimics their smart phone.
The largest use of a GPS by far in a watch is for physical fitness tracking I would imagine. In my mind if Garmin simply put an mp3 player in their GPS watches and added detachable mounts to be able to carry it on the upper arm etc., that would be the ticket.
What are you going to do with a smart watch, shake your wrist to wake it up, look down to see you have a text, and then pull out your phone to reply? Seems silly to me.