Why would you want to buy Envisioneer over AutoCad, Graphisoft or some other high end design package?
If your main interest is Residential or small commercial design
You want your design in native dwg format to share.
You want to import designs in dwg, dxf, 3ds in 2-D or 3-D
You don't want to spend thousands of $$ to get into a program
You want an easy to use program with a very short learning curve
You want 3-D design built-in but want to draw in 2-D
You want to incorporate real world products into your design
You want to be able to make animations from right inside the same program
You want to perform light studies from right inside the program
You want to do landscape design with the same program
You want to import 3-D elements in standard dwg, dxf or 3ds formats
You want in-office training for your staff
You want a viewer to give to your customers so that they can walk through the design on their own computer and change out appliances, change siding colors, roofing, wall coverings etc.
You want to generate your own materials lists, window and door schedules and blueprints
You want to generate your own 2-D high quality photo renderings of your design