I'm running Sailfish 3 at the moment after a catastrophic screen fail on my old Nokia 950XL (AMOLED screens have a horrible habit of screens rapidly creeping to black if damaged, otherwise they are techically awesome). I have a bit of a history of using niche OS's on PC's and phones !
It is very simple to install from Android 8, literally 10 minutes once you have the files on your PC. Once installed and running there is a normal set up series of questions that take a minute or so to complete and you're in. Sailfish is very very smooth and slick, and given the relative performance boost of Linux gives you an exceptionally fast and snappy OS which does real multi-tasking which probably isn't much of a feature for most users but can be handy sometimes.
The swipe based system takes a little bit of getting used to but actually feels quite 'normal' very quickly, have a look at any of the you-tube videos to see this.
The live tile home page is quite neat too.
The thing I like is that I'm not tied to an OS ecosystem that constantly wants to know what I'm doing, where I am or what I've been looking at .... By that I mean have you ever had that spooky experience where you talk about something with your phone nearby and then all of a sudden you get adverts popping up on web pages you browse??
Oh and did I mention that it also runs an Android emulator?