As a behavior analyst I have worked with many children with ADHD. I, myself, have a mild form of ADHD. In my experience, between medication, lack of empathy on the part of teachers and other adults, parents getting fed up constantly with them, etc. children with ADHD become under performers, act up, get in trouble often, and get used to fail.
Very intelligent children with ADHD have the advantage that they learn with a glance at the books or by listenning to an explanation. These kids are often popular, have friends in different groups, succeed whenever they want, and perform unevenly in areas they are not interested. For instance, if they don't like history, they will flunk one test and ace another, to average a passing grade.
Creativity is not a consequence of ADHD. However, when a child with ADHD is very intelligent and or creative, it tends to become noticeable by the uneveness of his performance and moments of brilliance.