"WordPress 4.0 Benny" released. Is this final and stable version? Should I upgrade to this?
Yes. I notice that upgrade is offered in the Dashboard. Remember to back up first - site and database.
I always upgrade on a test site and make sure there's no big issues before going to a live site to update. Might even wait for 4.0.1
and I have to say I applaud Karl's defensive approach, which I try to adhere to myself with varying success, I have to say that I''ve never yet had an issue with an upgrade.