I would use to create fluid levels in a way that is impossible with WED, this is because I could actually see the level before building it and therefore be able to create a sense of realism that again, would be impossible in WED. This program would allow for rubble to be placed in a more seemingly random fasion and would save countless hours of re-building for me as I have to adjust tiny little things one build at a time. Another bonus would be visualisation, this tool appeals to people who find it difficult to visualize perspeective images into a 3d picture because it erases the need for that skill and allows you to concentrate on what matters, the level itself!