Currently writing this on a fairphone 4.
I love the hardware aside from the camera, but that was a sacrifice I knew I was making going in to it.
My big complaint is the software. It has never really been fully stable. During the best patches things work most of the time, but there have also been some pretty bad bugs. Again, I knew the updates would be slower and bugs might take longer to fix due to a smaller Dev team but I didn't expect it to be this bad. It does feel like they just gave up on the 4 to work on the 5 and 6. At this point I'm 2 major android versions behind.
I love that when I broke the screen I was able to replace it in 5 minutes, and I want to be a big supporter of fairphone. I even went to the trouble of importing the phone and replacement parts to Canada.
I don't know if this is also an issue with custom ROMS but if this doesn't change I don't know that I'll get another when the time comes.