Although still in development it lacks accurate documentation but the community is very helpful in answering questions to get you going until the final release that will include a full manual.
I would rate this as one of my top picks for any level editor. The engines dynamic lighting makes working with lighting effects on props painless in making your environment come alive.
The dynamic lighting in the engine is the cherry on top with varying shadowing effects from faces and props (Animated fan shadows are unbelievable).
The engine really sets it's self apart from all others.