Thank you @RedwoodRiver for asking this relevant question. Here is my experience:
I have used the same old Nokia 5140i for 19 years. I wanted to keep it longer but the end of 2G in France has forced me to leave the only phone I ever bought two weeks ago. 
These last years, people who see my phone initiate interesting conversations about how one can live without a smartphone. It definitely confirm me to not buy one. Then I started to look for alternatives, and think about my needs.
Even if I was happy with my dumbphone, I had to admit I missed some features:
- a conversation history (and a little more than only 200 SMS in memory!),
- the ability to take, send and receive simple photos (which I had 19 years ago in 400x600 px format – another time!),
- some maps when I look for a street in town (my Nokia had a compass which helped me several times
), - and internet tethering (I often compensate the absence of smartphone by traveling with my computer… and begging for Wifi or somebody else’s tethering).
On the other hand it was clear to me I didn’t want:
- any Google stuff
- to spend time on it
- social medias, infinite scrolling…
- to get an instant answer to all my questions through internet
- to be short of battery every two days (my Nokia last 5 days – I had the battery replaced only once!)
My research for alternatives made me realize the Kompakt check all the boxes.
And there is more: to be honest, I felt like leaving my old dumb phone is leaving a part of my identity: my friends, my family, my students… I was known as the one who still uses this old crazy Nokia phone and I started to like it. It was a good way to promote a moderate way of life, and initiate dialogue about the use of technology.
Thus it seemed to me this e-ink screen was a good way to stay in this path.
I haven’t side loaded anything for now, but I like the fact that it is possible if I (really) need to.
Only 2 regrets for now:
- I fight for two weeks with a problem of low voice volume which made my calls a nightmare. I hope I will quickly find a solution with the support team.
- the OS is not open-source
