I had a PebbleTime back in the day. It was such an awesome watch. 7ish days of battery with an always on display that had no glare (all because of e-ink). All the foundations of a smart watch, to me at least, like notifications, text response, weather, etc were just done so well.

Keep in mind that an always on smart watch that had good battery was (as far as I know) non-existent at the time. Now, the Apple Watch is fantastic and getting about a day and a half is plenty for me, but it wasn't until just recently that I had anything to fill the space that was left on my wrist after my Pebble left me.

I still have that Pebble Time, and I'll get it from my parent's home next time I visit. I absolutely loved that thing.

Would I switch back to it? Probably not, just because I'm a very happy Apple Watch user now, but if I was still on Android, I wouldn't think twice.

Edit: Thanks to the replies that clarify the difference between e-ink and e-paper. I always forget what the difference is, but I'll have to keep the insight in mind for the future!