About three weeks ago I bought a Pebble. When a colleague of mine ordered the new Pebble Steel I could not resist and buy his old one from him. I will now give a short summary of how the first three weeks with it worked out.
Let's start with the most important thing for me. I would not have bought the Pebble if I didn't plan to use it for running. I already use Runkeeper to track every run for quite a while and the app supports the Pebble very well. As I always have my phone in a belt around my waist I can now see my actual time and distance with just a short look on the Pebble. I also can control the music I am listening to or pause and continue the actual workout.
The second thing I use the Pebble for is notifications from my iPhone. This is really comfortable in lots of situations because I don't have to take my phone out of my pocket everytime something happens. But it can also be a bit annoying if you get a lot of notifications, especially if vibration is enabled. Unfortunately it is not possible to disable certain notifications exclusively on the Pebble. You always get every notification which also appears on the homescreen of your iPhone. However this was also a good reason to have a look at all the apps which were allowed to send me notifications (which were a lot) and disable all I don't really need.
Of course I also had a look on some apps for the Pebble but I must admit that I didn't use any of them for more than testing. Yes, I can for example check in to Foursquare directly from my watch now but I think it is more comfortable and maybe even faster to simply do this on my phone. Maybe I will try one of the navigation apps for the Pebble because I can imagine that this can sometimes be useful for biking through the city. There are also some apps for activity tracking available in the Pebble App Store but as apps can't run in the background at the moment they don't make much sense. I hope that Pebble itself will integrate such functionality into the OS in the future.
Thanks to the e-ink display the battery of the Pebble usually lasts for about 5 days, which I think is quite decent. A smartwatch I had to load every night or which might not even last a whole day of use would not make sense for me. Regarding the iPhone I can't recognize any negative influence on its battery since using the Pebble. As I started enabling the Do Not Disturb mode on my iPhone more often to get notifications exclusively on the Pebble it may even last a bit longer.
After two weeks of using the Pebble I can say that it does exactly what I expected - but that's it. The two things I mostly use it for work pretty good. But until now I didn't find an additional "killer" usecase I couldn't think of before buying it. Maybe this will change in the future. There seems to be a good progress both with the Pebble software itself and the support for third party developers. The whole device category is still in the absolute beginning and I am very looking forward to see if Apple also comes out with a smartwatch this year.