Vertigo? Do you fear heights in a balloon?
The balloon only drifts slowly with the winds and that is why you will feel no airsickness.
Also you will experience no fear of heights as the balloon is loose from the ground. Because the balloon is loose from the ground your mind doesn’t have a reference (like you might experience on top of a high building) and therefore your mind doesn’t give some kind of signal that you are high up in the air.
The feeling of ballooning is mostly described as ultimately relaxing and experiencing amazing beauty of views. Also you will wonder about the principle of ballooning as the only thing that moves you horizontally is the wind and the pilot can control the balloon’s height in centimeters.