I'm sending this screencapture to illustrate the simplicity of ArchiLumos and it is it's plus and minus. If you are feeling at home with MAX or C4D, you will hardly compromise it's tool like this, but if you are average ArchiCAD user or beginner who wants more you'll consider having it.
I like Lumos 'cause it has interface, results and speed similar to Lightscape but of course I'm not happy I don't have Caustic, multiple texture layering, etc...
The fact that so many of you guys are talking about this tool says that we need stronger rendering engine inside ArchiCAD. I would be happier if Graphisoft bought Lightscape instead of AutoDesk.