As yellow said, if it’s properly mixed, the effect is to be a very sweet iced tea taste where the alcohol is nearly unnoticeable. It’s probably due to the mixer/syrup just obliterating the harshness of the alcohol. Before I gave up drinking, it was definitely one of the few drinks that could sneak up and kick you in the ass if you weren’t paying attention.

The fact of sweet mixed drinks getting into you faster likely is also a contributing factor, and the classic liquors that they use are ‘sugar heavy.’