The key features to make a 'smartwach' worth my money, in my mind, starting from the hardware side:
1. E-ink display. Easy to read in daylight, can be illuminated from the side for low light use, extremely low power use.
2. Inductive charging. I need to be able to take my watch off and set it down on a stand, and pick it up in the morning knowing its charged, no fiddling with little connectors that get corroded by my personal humidity.
3. Decent water resistance. This is an extension of number 2, but vital. I need to be able to sweat, wash my hands, slosh a drink, and not be worried about ruining a multi hundred dollar piece of hardware strapped to my hand.
as for software features, I desire:
1. Show me the time without having to screw with it. - I don't want to be pressing buttons on my watch just to see the time during the day. At night, yes, a button for a light, but I need it to be a 'at a glance' function.
2. caller ID function, and ignore call function. This thing is linked to my phone, so most of its point is to be able, at a glance, to see who is calling me, and ignore the call if desired. Single dedicated button for this function would be best.
3. Volume control for headphones attached to phone. - say, I have my phone in a pocket/arm case, using headphones to listen to music or make calls. digging the phone out to change volume, or fiddling with tiny buttons on the side of my head at my headset sucks, It would be nice to be able to use a volume control on my wrist to adjust the volume of whatever i'm using. Remember, this 'watch' is supposed to be an extension of my phone. basic pause/play/skip function would be nice also.
Honestly, thats about it. The main thing that makes me dislike the current smart watch offerings is bulk, charging, and over-feature. There are very few things I will want to do on a screen small enough to fit on my wrist comfortably, and as such, I see the smart watch as more of a peripheral device, not a primary interaction vector for my devices.