I'm not OP, but I've had the opposite experience: I'm not using mine anymore.
I have both the original Pebble and the Pebble Time, but I've abandoned them in favor of a Suunto Ambit 3.
It functions well enough as a basic smartwatch (it can receive notifications, and that's about it) and fitness tracker, but is far better as a running watch: it records and displays more metrics, with far greater accuracy. Since it is also my fitness tracker, I'm wearing it every day instead of the Pebble, because I don't want two sets of incomplete data.
It's far more important to me to have a watch that functions as a running watch than one that has smartwatch features.
Wearing it as I type right now. But that's because all of my Garmin watches (610 and 910, IIRC) are old enough to not have the smart watch stuff. If I had a 920, I'd ditch the Pebble. I just can't yet justify the $400 simply to aggregate my wrist-worn devices.
Big handfuls, you'll get about 8 days out of it, less a day for every 30 minutes of running.
Garmin have released a few firmware updates for the watch which may account for the difference between my findings and those of early adopters.
It uses more battery life, but in a lot of cases it's the difference between accurate positioning and not.
So, yeah, I'd try doing same day runs on clear days, with GLONASS on and off, and compare drain rate.