Rasengan has the same flaw the way Naruto uses it (since he hasn't mastered the ability to form is spontaneously like Jiraya can), except Naruto, instead of using the sharingan (and speed, but with the sharingan, the users speed need only be comperable to the opponents, not extremely fast) to avoid enemy counter attacks, he uses something like kage bunshins, etc... to make an opening to attack.