I have no imminent plans to purchase Apple's new smartwatch, but for a while now I've thought that my technology usage patterns would make me a good fit. When out and about, a smartphone seems pretty optimal. A watch won't add much value here (unless the fitness tracking and haptic functionality really takes off).
But at home, work, a coffee shop, I see room for improvement. Whenever possible I conduct online business on my laptop. This includes social media activities and various messaging channels. Push notifications are key here: I'll carry my phone around just to alert me to a notification. When a relevant one pops up, I'll switch to my laptop.
The bottom line is this: for a decently large chunk of my smartphone activity, the phone is acting only as a device for notifications. Nothing more. A smartwatch would perform this laptop-augmenting function just as effectively, and eliminate the need to constantly move smartphones--which are increasingly becoming massive tablets--all around the house, apartment, coffee shop table, etc.