It leaves the paint very smooth. It's a lot of work, but if your paint still feels rough to the touch after you wash the car, it's well worth the time spent. It's one of those chores that you should plan on spending the entire day doing, including waxing the car afterwards. And don't drop the clay bar on the ground - you'll have to throw it away, because you don't want any foreign contaminants it may pick up scratching the paint.