Have been with Studio One since....err...1. I have never completely gotten used to the dark background that started with 3, and wish they would go back to the 2 colors. For me, the primary criteria for a DAW GUI is that 1) the DAW’s functions should all be logically located and easily accessible; and 2) it should be ergonomically easy on the eyes. I do not care at all if its color scheme is trendy or even pretty (so long as it is not flat out butt ugly).