I love simple smartwatches that are hackable. I got my first and second Pebble as part of their Kickstarter campaign. I was a pleased user until then shut shop. I continued my search for a smartwatch. I had two options in front of me Bangel.js 2 and PineTime. I got both of them. But my PineTime is a developer, early version. Hence Bangle.js became the official replacement for Pebble; also got through a Kickstarter campaign.
This makes it a great device to hack and do whatever you want. The latest release has native integration with Gadgetbridge; it can interact reasonably well with Android devices. Bangle.js support in Gadgetbridge came directly from Gordon Williams, the watchmaker, and Espruino. This shows his commitment to the community and FOSS. In the last six to eight months, there have been quite a few updates to firmware, and it makes the watch better and better. Even the way to upgrade the firmware has improved.
If you are a hacker, if you want to play with your watch dangerously, or if you want to teach your child programming, the Bangle.js 2 is a great watch.
In my opinion, it's a spiritual successor to Pebble Time. We need a bit more polishing on the OS front but way ahead in terms of openness and community.
Also now I am comfortable with this watch, expect how-tos.