1. It should have been explained better why there was only supposed to be one soul at the accident. (Was it because the friend wasn't expected to show up? Or maybe because the main character wasn't expected to show up?) An adequate explanation is necessary for the main character's actions to make more sense from the reader's point of view.
2. The main character's callousness just doesn't seem right for the story. He doesn't seem to care much that his best friend from childhood, who cared enough to keep their promise to meet again even though he became rich and famous, is dead (possibly in the main character's place, too). He doesn't seem bothered that he's using his dead friend's body, either. Making the reader care about the main character is important to a story, so it was a bad decision to have him act this way when he finds out about his close friend's death, because it makes him seem like a jerk instead.
3. The character design for the angel is just awful. What an ugly thing. Maybe it being ugly is supposed to be comical, but if so, it should have been better indicated in the story that that was the case.
4. The message of the story is supposed to be about living one's dream, but because of the plot, in which the main character ends up having to die and use his dead friend's body in order to do that (which means, it was impossible for him to accomplish his dream as himself), it just doesn't come out right.