If you watch TheQuantifiedScientist you must have found out by now that optical sensors on the wrist have no chance of ever being accurate enough for health and fitness tracking. No matter how much they massage their algorithms they simply don't have the right sensors at the right positions on the body.
At the same time the fitness features add cost, bulk, the uncomfortable sensor bump and cost battery life. The original Pebble didn't have any of that and in my opinion was better for it. I also see little point in competing with the already existing numerous options for fitness tracking, even if you only look at the ones without a subscription.
I've watched it and TheQuantifiedScientist is totally missing the point. Current optical sensors on the wrist are plenty accurate enough for general health and fitness tracking. If you don't believe me then you can literally count your pulse with your finger and compare against the watch: very close. Optical sensors aren't great for high-intensity training so for those activities everyone knows you need to use a chest strap if you want accurate data.
For a more practical take on heart rate accuracy see the DC Rainmaker reviews instead.
At the same time the fitness features add cost, bulk, the uncomfortable sensor bump and cost battery life. The original Pebble didn't have any of that and in my opinion was better for it. I also see little point in competing with the already existing numerous options for fitness tracking, even if you only look at the ones without a subscription.