I had the chance to pick up Driftmoon today, and made a point of exploring the toolkit that is integrated into the game. Overall, it's a bit rough, and I wish there was some way to pitch the camera angle downward from straight overhead. (Maybe there is and I just haven't found it yet.) Even so, it has some real potential. Here's my initial observations on some of the basic functions of the editor.
Terrain editing: This is very simple. Water seems to be at a fixed elevation; I'm not sure if things like higher-altitude rivers or waterfalls are possible yet. If you dig down far enough, you find water, and the "beach" texture is automatically applied between the land and the water. Rock features are automatically added to sufficiently steep inclines, and rock textures are applied to cliffs too, it seems. The interface for raising and lowering terrain is a bit strange to behold at first, but once you realize that it's showing you the altitudes of individual cells, it becomes rather intuitive to use.
Also, the game seems to have an area-based world, rather than an open world, although it apparently boasts an absolutely sweet overland map system. I'm not sure if things like boating on water are possible.
Placing scenery objects: This is a bit convoluted. Every scenery object begins its life as a nondescript block that you a) apply textures to and b) re-shape into whatever it is you happen to need in a particular position. Once created, scenery objects can be given a large number of properties and, apparently, roles, although attaching scripting to an object doesn't seem to be possible. That, or I didn't notice the button that opened up the scripting interface.
Placing actors: This is straightforward enough. You place an actor, choose his or her appearance, determine whether he or she is the player or an NPC, and then assign him or her a faction (friendly, enemy, etc.). I'm not sure if multiple factions can be selected. You can also give actors a set of starting equipment, although the game doesn't appear to support paperdolling.
Scripting: Scripting is done through a visual interface, basically. You select when a script triggers first-off. It would appear the default script architecture is a basic if/else conditional; I'm not sure if other logical types are supported. For an if/else statement, you select the conditional (wide range of choices here), and then select the "if" action and the "else" action. Or actions, perhaps. Thus far, it appears that scripts can only be bound to actors, although I'm sure that can't be the case (or else Driftmoon is an RPG without "FedEx" missions...).
Sound: I didn't explore sound too much, but it would appear that sound sets can be laid out on a cell-by-cell basis in areas. That is actually a very granular level of control, and could probably be used to create some interesting effects.
Effects: These are placed like objects, it would seem, with manipulable radii. I didn't mess with these too much.
Overall, the editor has a lot of potential, but also some fairly obvious limitations as well, not the least of which is the lack of polish and clear documentation. If you click around, you can find stuff, but it's not always easy to intuit where a particular function is located in the editor's set of button-style controls. As well, some of the interfaces -- the script editor, most notably -- are rather clumsily laid out. And you have to get yourself into the habit of doing an alternating right-click/left-click procedure in order to dismiss one dialogue and then select an object to manipulate. Relying on the menu buttons too heavily to move between the different editing panes will result in the creation of many spurious actors and objects.
Still...once you get the hang of its quirks, it's probably quite easy to use the Driftmoon editor to rapidly create very complex set-pieces with this thing. It looks nice, too...not a "next-gen" thing by any means, but definitely enough for storytelling purposes.
And sharing mods is simple...like...click-of-a-button simple. Once you're in the game, you're connected to the modding community; uploading a mod and downloading mods is easy-peasy, and mods that make heavy use of the game's default assets tend to be pretty light downloads as a result.