This model (no. 83888-se) has eight different settings, which I've had time to experiment with. When drying your roots, keep the dryer on the middle or lowest heat setting, and at the lowest speed. This setting is perfect for the hair close to your scalp, keeping your skin from burning, and to create smooth face framing results.
For drying the middle sections and tips, use the high speed setting, with either the medium or high heat setting. This will result in faster drying time, and smooth out the ends of your hair.
Overall, this beauty wonder has kept my hair from that dreaded blowdryer "blowout" we all have grown to hate.