How to put this... the story really hit home for me. Many of the poorer scores gave it so because they went into the movie thinking it was a comedy or a blockbuster romantic comedy. This isn't an "Anchorman" nor a "You've Got Mail." Its not built around the laughs (it never really draws a straight out HA-HA from any scene) and it doesn't have the gloss and "fakeness" of a big-budget Hollywood romance. This movie is...very Wes Anderson lite.
The story itself is there for people that are likely older than 20 (though for anyone that feels like they went through a troubled relationship maybe as well). Someone has their life, which they were basically coasting through, suddenly kick in a manner where even they cannot simply ignore it. While a marital problem is more romance comedy-esque the story could have rolled along with a job problem, financial issues, a disease, or any other narrative that forces the main character to stop and listen.
This kick leads to a decline in morale and habits but ultimately, through seeing how low they have gotten, a change of pace. Its been done over and over again in stories throughout all genres, but that doesn't make it any less true or compelling.
Very attractive female leads helped to make me care more about the story because, lets be honest, if you see a male or female that you are not attracted to in a movie you are going to care less about the "guy getting the girl" when you envision yourself as the lead character.
Finally the sharp but realistic contrast between "overweight" Bill and "happy" Bill was one of my favorite parts of the movie... bad things kept happening but he was pushing and had a goal. Maybe he didn't even realize it was his goal but the shedding of his conspicuous apron-tummy and happiness with his own self image are the starting grounds of all change. You cannot make others truly happy unless you are happy . Maybe that is why he has the marital issues in the first place, but the fact that he finally is able to go off and have a CHANCE (he might die next time he carries 200 lbs of fireworks into a car accident) at a happy life and in some ways a small "re-do"
TL;DR - Has a few moments that make you smile and chuckle but you won't need to worry about spitting soda on your screen. While there is a clear "romance" to story, at the end, the romance is more with himself than others (and not in a narcissistic way). Worth a watch and I'd recommend to anyone that likes indie films or relates to someone down on their luck that wants a chance to change, but if you don't fit into those categories or come in expecting a "laughrorious chucklefest" you may leave disappointed.