I used to wear a Pebble watch every day and found it useful but not overly so. That needed charging every 5-7 days, and this claims to last a week on a single charge. I don't wear the pebble watch any more because as lazy as it sounds, I kept forgetting to charge it when it ran out of battery, and there were days where I was walking around with a dead watch, which was at that point essentially an expensive wristband.

With my phone, I know I need to charge it every day and it is a habit to plug it in just before I go to sleep every day. With the pebble, and I think this too, sometimes the battery would last 5 days, sometimes 8, and that irregular charging cycles means it's hard to form habits around charging.

It became annoying to remember to charge the Pebble and take it off and put it on again. The benefits from having it became less appealing. I fear the same might happen with this if I were to own it, and it would become a bulky iPhone case. At $129 it might be worth a punt but I'm skeptical.