This movie, in its structure, reminded me of John Woo's Once A Thief. A Thief, Woo tries to blend romantic comedy with his incredible action but it never quite works.
Heart of Dragon is a victim of the same thing.
The dramatics are good, in fact incredible at times, with Sammo playing Jackie's retarded brother. Jackie gives a good performance as the driven cop who will stop at nothing to get his brother back when he is kidnapped. The action scenes are also extremely well done, with an exciting car chase and a blistering finale that really lets Jackie cut loose. The intense action doesn't mesh well with the overall film. This is my only complaint however, as Sammo did a wonderful job in front of and behind the camera, as usual.