As it is, it's totally unusable.
I checked, and yes, it actually loads if you exit the game. Nice feature.
Starting Locations seem to be totally uneditable. Due to the awesome saving mechanism, I have some in the middle of the ocean which can't be removed by any means.
Tile modifications (which BTW, seems to be the way to add essence) only show up after reloading. Which is great because of course that means exiting the game. I'm guessing a number of other modifications work this way.
After simply failing to do even those two simple things, I am going to take the short cut and say while I see some things do work (like I can place shards) that probably a whole lot of other things are bugged.
Seriously - there was no point in including this feature on release. I feel Stardock owes me some time of my life back wasted trying to do anything with this tool