I bought an original Pebble and wore it 24/7 for a while, tracking my sleep. What I found amusing was that I didn't find the sleep tracking all that useful, nor the notifications and apps - but having a very small LED torch on my wrist which lit up with a wrist-flick was incredibly useful when quietly navigating a dark apartment at night!

If I were building my own smartwatch, I'd give it a bright gesture-activated LED light aimed at my fingers.

In general though, I liked the Pebble, but didn't find it useful. I gave it to my partner, who's a horticulturist and spends a lot of time up to his wrists in soil - he loved it because it let him figure out which notifications were important enough to clean off his hands and pull out his phone, and which could be ignored.