I'm late to the party but wanted to share my point of view anyways - I watched BIWHM this summer. I admit I'm not familiar with David Foster Wallace's work (though I'd really like to read at least this one) and would probably not have watched the movie if it wasn't for John.
I'm really glad I did though, because I really liked it, I was pleasantly surprised by the way some scenes were staged and by some camera shots. This is not the type of movie I'd rewatch over and over (even if I'm certainly going to watch it a second time, because I'm sure there's more to take about it after a second viewing) but I may stop at certain scenes who are really well done.
Someone here expressed how talented John was in his monologue to make us hate him a little, and I have to agree: his acting here is nothing but fantastic and it was weird but at the same time refreshing to see it deliver such a performance. I don't know if he is the most hideous man of all, but I do know that I was at some points in the movie uncomfortable or annoyed with Sara, but I was with her on this one. And I have to admit, this scene and their storyline in general stages really well the awkwardness of a break-up, involving or not a third party. I thought it captured really well the looks and uneasiness and anger two persons can have.