Very neat- there's a lot more I wanted from the game, but I really like the idea of world-sim voyeurism.
Someone mentioned the activity animations, and I agree, I think that's my favorite part. Anything from Goblins talking to eachother, or rare happenings might make the early game waiting for more goblins interesting.
There's a million suggestions I keep thinking of, from menu-hotkeys, to job preferences - but all these suggestions just come from a place of wanting to see both more content and more polish.