I have been using SailfishOS phones as my main driver for ten years now. Some random, personal, possibly uninformed thoughts:

- It is not for everyone. Some Linux experience and willingness to tinker with it is helpful.

- Despite the many limitations, I love the UI, the spirit, the platform, and the community. I fear the day where I have to switch to a different OS.

- Many Android apps can be run via the AlienDalvik/AppSupport middleware. However, raw BLE is not supported. Thus, most e-scooter apps won't work. My banking app runs okay-ish.

- Google Play Store and Google Play Services can be installed by following non-trivial tutorials. I don't use them.

- The hardware abstraction layer that makes proprietary Android drivers work with SailfishOS is cool.

- QML and C++/Python/JS allow for easy, rapid app development. The custom widgets have a unique, consistent, simple style.

- As most of the UI is written in QML, it is possible to adjust and extend most of the UI shell and the base applications just by editing these resource files on the phone. For example, one can add additional widgets to the lock screen or change animation speeds.

- A nice tool, Patch Manager allows transparently and reversibly applying such modifications. This is so cool, even though the patches often have to be adapted for each major OS version.

- Jolla, the Finnish company behind SailfishOS is tiny and had to let go a lot of engineers and supporting staff a few years ago. Development has slowed down significantly.

- There are about two dozen very active developers in the community who write awesome apps. There are native clients for Discord (no voice/video), Signal, Telegram, Slack, Mastodon, Hacker News, etc.

- Unfortunately, the browser is stuck with outdated Gecko (despite heroic efforts by a developer who upgraded it from ESR 78 to ESR 91 [1]).

- Only a few smartphones are supported by SailfishOS - either officially supported by Jolla (e.g., some Sony phones and some Jolla-branded ones) or supported via community ports. Often the hardware support is a little bit buggy.

EDIT: of course, if you visit the forums, you will see quite some criticism of Jolla - and some of it is well deserved. It would be great if there were better hardware, fewer bugs, better support for Android apps, etc. Personally, I feel that Jolla is really trying to make SailfishOS better but that they lack really stable sources of income and have made some less-than-ideal decisions in hindsight. The best solution would be to get EU funding for stabilizing the platform and finding a business model that generates recurring income from large organizations. Selling to private customers without being able to extract recurring income and being dependent on badly-documented hardware is not going to work.

[1] https://www.flypig.co.uk/?to=gecko&list_id=975&list=gecko