Funny I was just wanted to try their 3D World Studio editor.

I am not a pro at this but from what I read is that with version 3 they also integrated the 3D World Studio (instead of using it as a standalone program). That editor seems very similar to the Hammer editor (which seems to user friendly). Though I can't speak from first hand experience yet and am not familiar with LUA.

It seems like an interesting engine. Also it is royalty-free like Gamestudio3D.

ps: I am also interested in hearing other people's opinions about Leadwerks