As a Thunderbird and K-9 user this is 51% good news and 49% possibly bad new. Good news because it should increase the chances that the two products will live a longer life. Possibly bad news because I'm one of the crowd that went back to K-9 5.600 because the new version destroyed the UI that was the primary reason why we picked K-9 over other apps. 100% self selection bias here. There was maybe an ongoing effort to…
I actually stopped using K9 because it stuck to the ridiculously outdated, and honestly quite ugly, Holo interface. Holo worked as long as the entire system was consistent, but as soon as material design got fixed in Android 7 (took them a while to cut down on the margins!) I was over Holo. I don't feel like setting up my mail client again but looking at the current design I'm pleasantly surprised. I'll probably give…
Personally, it was the transition from Holo to Material that drove me off Android entirely. There was no such thing as dark mode at the time Android 5 dropped; you had to set brightness very low to stand a chance at reading anything in the dark, and with many (almost all?) apps still using the dark Holo, looking at and using the device was jarring. I switched to Jolla, and later to iOS.
I'm happy Android users didn't have to suffer through another platform-wide redesign in the meantime, but I personally don't find Material appealing.