This movie is definitely a dark comedy -- as some of the other reviews reveal, Ryan Reynold's character has everything go miserably wrong in his life. The irony is that he is an efficiency expert and, prior to this series of events, had an inordinately structured and "perfect" existence. When it shatters apart, he begins doing the some of the risky behavior he once condemned (driving a Harley with no helmet) and smoking. You can feel the tension because his actions go against his personality. Throughout, Reynolds is very convincing in dramatizing the stress and anxiety.
Just watching the film, I could not help but feel very empathetic toward Reynold's character. To me, it isn't really all that "laugh-out-loud" funny. Rather, it is more of a sense of shock that the poor guy has been devastated so badly and deeply.
While I normally don't like this kind of movie, I felt it was strangely compelling and well done for what it is. Just don't watch this for some light-hearted laughs.