His style of play is quite traditional as a full forward, often getting on the end of passes, and scoring with his preferred left foot. It's his superior physical strength that sets him apart from his peers, coupled with his agility on the ball, making him very difficult to mark.
O'Neill announced his retirement from the Tyrone Gaelic football team in January 2008, but made himself available for the All-Ireland final of the same year. Tyrone won the competition, but O'Neill refused to accept the medal, citing the fact that he felt he had not earned it, having not been part of the team on their journey to the final.