I was a Kickstarter backer and have had my Pebble for a while now, and honestly have not been super impressed with it's "functionality," but have loved it as a geeky tool for reading texts and tracking baseball scores. This is all to say, I share some of the skepticism about the device, especially since I have one.
That said, this was the feature I was most excited for, and even in this limited first implementation, it delivers for me. Like anything, this is always going to be based on your own strategies.
1. Running. At the most basic level, this thing saves a ton of battery life on your phone. Even though you are cranking GPS + Bluetooth, being able to have your big shiny screen entirely off during your whole run makes a measurable difference. There is also comfort: if you wear your phone on an armband, there is nothing particularly nice about trying to look at your upper arm mid-stride. Glancing at your wrist is more comfortable, even if you get slightly less information.
2. Cycling. I'm a commuter, not a competitive rider, so this is actually where the app shines for me. I don't want a huge iPhone mount on my handlebars, so this allows me to start tracking my ride, put the phone in my pocket, and then not worry about it again. I actually think that Runkeeper's "Auto Pause" functionality is pretty good, but since you can start and stop directly from the Pebble, my route this morning was measured with more accuracy. If I wore a jersey or something, I could imagine slipping the phone in a back pocket and then not having to look at it.
Again, a lot more could be done here—it's crazy to me that they chose to show average pace instead of current pace, and no heart rate info—but hopefully that will come over time. I just wanted to share these use cases for people legitimately curious. I understand that this reiterates a lot of what has already been said in this thread, but I guess I just wanted to spell it out a bit.
