Earlier quoted context omitted.
The problem is that eInk is relatively slow (I know the newer versions are much faster than the old 500ms ones) and can't do color (well).
Don't care. I would be ok with a watch without a second hand and the slight sub-second delay of eInk for displaying notifications. And a lack of color too. Especially if it meant that I got 10x the battery life (which it would).
eInk has serious benefits, especially when it comes to battery life. I love my Kindle. I can see how something like the Pebble would be a nice watch and eInk's battery drain is probably a big part of what makes it work so well.
But if you want it to feel interactive with a nice touch screen for swipes, eInk isn't going to do it. Take that video but change all the animations to 5 fps... would it be an amazing watch or just feel like a product that was reaching too far?
Similarly, color is a nice add but it could go wrong. The only pictures of color eInk I've seen look much worse than cheap newsprint. At that point the color isn't adding much, it's just detracting.
Samsung supposedly has much better battery life on the Gear 2. Keeping the display off most of the time would definitely help too. I want to see a review of this. If it's half as cool as it looks in their promo I'll be quite impressed.