Lack of GPS is the dealbreaker for me. Otherwise this would be an insta purchase -- I bought the Time in 2014, and was hoping for a "smartstrap" with GPS back then, but when it never came I slightly lost interest.
With a GPS (GNSS) receiver on the watch you can get instant position and speed data without having to maintain a stable Bluetooth connection to the phone. Some athletes prefer to record activities on a watch without having to bring a phone. And in certain races, such as most sanctioned triathlons, phones aren't allowed on the course at all.
Or to put it another way: a Pebble would cover more uses with a GPS. They're clearly not expensive nor necessarily profligate with battery. My now 5 year old Amazfit bip, which was cheap as chips, still gets 3 weeks of battery life with a daily gps-mapped run.
