loaibassam Flarum is already stable to run, and we are committed to offering detailed update instructions all the way to stable. There are still some known bugs and limitations which you can find by reading the GitHub issues but if you can live with those Flarum will work fine. As pointed by katos many big websites have already chosen Flarum as their platform. Some of the biggest are listed here https://builtwithflarum.com/
What might block you from updating are third-party extensions. As long as you use trusted and maintained third-party extensions you should be fine. And even if an extension you need stopped being maintained by its original author, you can usually find someone who will update it for a fee.
How difficult updates are to perform usually comes down to how many and which extensions you use. The "cleanest" the forum is kept, the easier it is to update.
If you are going to develop your own custom extensions, keep in mind that the Extension API is currently being finalized and extensions might require changes on each subsequent beta release. We try documenting all changes as much as possible in the release notes for developers.
