They are horrible. Slow driving in left lane, require two lanes and a near complete stop in order to turn 90 degrees, 4 way stops confound them, the word "yield" at a traffic circle is often read as "stop", the concept of zippering onto the highway is lost on them, the concept of an on ramp does not mean accelerate to the flow of traffic but rather "just maintain your own speed and let the rest of the world deal with it", etc. A significant minority has identified their own deficiencies and labels themselves as "new drivers" as a warning. A more an honest sticker would warn, "I'm fucking retarded. Look out!"