E-paper, actually, which is a fairly broad umbrella for a lot of reflective LCD displays. E-ink is specifically from E Ink and uses a different display technology (it's what's used in Kindles, etc.).

This is probably a lost word-use game, as everybody just says e-ink, but it seems important given the major differences between reflective LCDs and the electrophoretic technology used in ereaders.

I had a MetaWatch watch with an e-paper display with silver reflective screen backing and it was, by far, the most comment-generating thing I've ever worn. Still miss it.

Mine still runs a week on one charge, could not find a substitute yet.

Once a week? I easily got a month of battery out of my Pebble (whatever the base model was). It was awesome, and I'm still bitter about the sellout to Fitbit. Now I have the Amazfit Bip which gives me around 35 days of battery between charges. I can't see myself buying one of these smart watches that requires a recharge every day or two, it's already annoying enough to recharge my phone and bluetooth headphones every day.