Smoother and better throttle response over the entire range. Most noticable to most at light throttle acceleration but to an enthusiast it would be noticable throughout the entire range.
If you want to see how well it works, try cleaning it chemically and drive it to see the difference then pull the upper intake off and have a look.
Try cleaning the throttle body first so that you can see just how dirty the rest of the intake manifold is before you do the chemical cleaning.
