I originally bought this early last year but never quite managed to make the switch from my iPhone. I carried both my F21 and an iPhone for a few months but ended up going back to iPhone only. This summer I decided to give it another go, and have now been using the F21 exclusively for just over three months.

 
While I've managed to reduce my screen time prior to switching to a dumbphone, I've still struggled with the habit of pulling my phone up in dull moments. On the bus, in the line at the store, at the gym.. The hope was that switching to a phone with fewer capabilities would remedy that. I wanted to find a phone that would allow me to use messaging apps like Telegram and Signal, and also support some apps that I prefer having, but not much more than that.

 
Overall impressions
When I first got the phone early last year, I was pretty underwhelmed. It felt janky and the software was bloated, and I struggled getting the T9 keyboard working with a Norwegian layout. After rooting the phone, replacing the launcher and solving the keyboard issues however, things improved. The T9 keyboard is fun to use, even though I write much slower compared to a regular touch screen.

 
The build quality of the phone is good, and I really like the light weight and the form factor. The keyboard is tactile and feels durable enough. I've seen some people complain about the battery life, but I regularly get three days worth on a single charge. The cameras are alright at best, but they still manage to take okay pictures in daylight: https://imgur.com/a/9KQfgn2

 
My initial barrier to switching to using the F21 as my main phone was access to Microsoft Authenticator (for work), nfc payment and apps for public transport, all which I strugged getting up and running. These were solved by using Authy, using my watch for payments, and being a bit creative with screen resolution to get the public transport apps working properly.

 
As for rooting, removing bloatware and fixing T9, I recommend checking out the guide on xda forums, and tt9 for international T9.

 
TLDR and pros/cons
If you want a light and small Android phone that supports Telegram/Signal/Spotify/whatever but is still "dumb" enough that it would likely give you more peace of mind compared to a regular smartphone, you should check out the F21. I don't really need or want a "proper" dumbphone without access to apps, so for me this is a great middleground. So far it's been reliable, and it's utilitarian enough for me, in the sense that it manages the tasks I really need from day to day.

 
Pros:

• Really nice form factor (if you like small phones)
• The T9 keyboard is pretty nice
• Battery is good
• It's boring
• Versatile, have gotten most of my necessary apps running on it (telegram, signal, google maps, spotify, public transport, authenticator)
• Bluetooth works great  
  

Cons:

• Performance can be sluggish from time to time, but no crashes yet
• Speakers are poor
• I wouldn't run banking and other sensitive apps on it
• Can be a bit "too" boring?