Does anyone use or have feedback on Sailfish?

I wish it was feasible to have alternative mobile systems, but it's not really.

You can't simply give up every popular app for a system nobody else uses or develops for.

Sailfish has Android emulation, but good luck running banking apps without Google SafetyNet. Even pure Android ROMs, like LineageOS, can't do that.

Also good luck with proprietary firmware for mobile networking and cameras. Another thing that usually holds back AOSP distributions, and will likely be even worse in a non-Android system.