There are a lot of videos of the earlier version of the editor in action. It is complicated and robust, but looks capable of creating quickly (with little detail) or creating intricately (taking time to do so). I am going to be building a custom world, and have used similar level designers before. I know they were refining the editor, and I also hope it releases a bit ahead of the September main launch date.
What I look forward to, and hope is available is an "a la carte" level database on the Steam community. So when someone needs a "creepy cellar" or a "medium tavern" those can be grabbed and modified to fit the GM's needs. I am willing to create every single nook and cranny, but if someone else does it and I can adapt it, that works as well.