There's something there, but it didn't work out. It's clearly supposed to be some kind of screwball black comedy, but the comedy isn't screwball enough or black enough, so it just comes off as a romcom that doesn't quite grasp how fucked up it is. Both Harry Connick Jr and Sarah Jessica Parker are terrible in it, no charisma or chemistry, and every single supporting character is more appealing to watch than either of them. The total lack of spark in the alleged romance just makes it uncomfortable when they act cute over the corpses of their victims. It should be comic, but they and their relationship are lifeless and that makes it creepy. The titular Dick is meant to be so unsympathetic that you're okay with the light-hearted shenanigans surrounding his murder, but he was still more engaging than our 'heroes' and the morbid absurdity which depends on us utterly hating him to become dark whimsy remains grim and upsetting.
Craig Ferguson has his moments of being quite funny, as does David Koechner, but their scenes working well doesn't pull the film up from its downward spiral. The leads are just ill-chosen or poorly directed or both. Their performances are straight bad and their characters have no charm. Sarah Jessica Parker as a bubbly blond with a secret knack for crime is supposed to be a funny dichotomy, but her baby voice and air headedness are just grating.
Harry Connick can't act and casting him as a heartthrob is also possibly just a bridge too far under any circumstances considering he looks like a Simpsons character. At their fucked up meet cute she differentiates him as 'the handsome one' and yeeesh. That's as cruel as the plot. The fact that he's standing next to Johnny Knoxville (far too good-looking and likeable for this role) at the time doesn't help. Casting Knoxville as the heel in general didn't work. As we find out the original motive to kill Dick was a misunderstanding, despite the film's constant reassurance that he's definitely still a complete asshole, his naturally endearing screen presence and the heroine's unhinged behaviour combine to make him just enough of a victim that the whole conceit of the film falls apart.
Anyway, the consistent awkwardness leads me to believe the biggest single problem with this is the director. It could have been mediocre rather than bad with the exact same script.