I have a Fairphone 4 since release. There where some bugs for the first couple of months. Now everything works as it should and I have no complaints regarding day to day usage. I am not using my phone for much more than messaging, navigation and some light web browsing though, so my experience might not be representative.
C4 is used at my company, and I am quite happy with it. There is also a open source DSL called Structurizr to create the diagrams in various formats.
Blogspam that links to a ‘news’ website that just regurgitates this reddit thread. Somebody explain to me why is this upvoted so heavily.