I haven't actually USED my Vintage Air system yet, but the installation looks great. I have a black dash and their molded under dash vents look really slick. Definitely cleaner looking than factory, but would need to be vinyl wrapped to TRULY look like a period installation. Either that or steel wool the housing so it isn't so shiny. The glossy look and texture are unlike anything else in the car.
The vents are small and unobtrusive.
That's my two cents from a visual perspective, anyway.