I believe Impression can add value to any designer's workflow. However, as an owner of AutoCad, Revit, SketchUp Pro and other similar programs I hope Adesk offers Impression at a 'reasonable' cost.
Right now, I see it's value somewhere in the SketchUp range but certainly not a player in the high rent district. Having said that, this is a simple to learn, easy to use product that fills a digital gap sorely needed. But if the cost becomes too high, well...back to the markers!