I have been using it as a daily driver since before it went beta. After the beta, I have found it quite stable. And recently it have been rock solid. There are still some things missing (like it would be nice with a calendar app, support for firmware upgrades and so on), and some things that are a bit rough. But overall I find it to be a quite good release, and since nothing comes close to their window management (the tiling implementation is really great) it compensates for any minor rough edges you might find.