Good to read.
It's actually easy to understand the mapping part (or maybe those are my "roots" in mapping making it easy for me) but I have more troubles figuring out how to modify certain stuff (locking a door with a key or alike). Stuff which should actually be easily achievable via tickboxes and tags in a properties window for example.
That's the only aspect where I see user-friendliness failing that would really profit from easy-to-use GUIs.
Well, some bugs aside... (sometimes camera movement locks forever or I cannot undo an action).
