Just watched it today... while I had a few hearty laughs... it features two of my most hated conventions.
1. "The Urkel" - In this case Alan... the character who is so completely horrible in their behavior that any and all characters would be completely justified in their hatred for and ostracism of but because said character displays a moment of intense vulnerability or weakness the audience, and therefore the main characters, are sucked into feeling sorry for them and forgiving their otherwise unforgivable behavior.
Michael Scott on The Office is a perfect example of that kind of character... in fact Steve Carrell played the same kind of character in Dinner For Shmucks. It's stupid and lazy and insulting and I'm tired of it.
2. The sacrifice of "non-essential" characters being overshadowed or ignored by the triumph of "essential" characters.
Teddy loses a finger presumably ending his prospects at becoming either a cello player or a surgeon. His life was in danger and he was forever disfigured..... but it's ok because Stu learned how to stand up to his domineering future Father-In-Law. We never get any kind of emotional resolution on Teddy's story just the obligatory "I know I almost died and you guys involved me in the kinds of activities that could not only have killed me but worse could have made my remaining life some kind of grotesque nightmare..... BUT I FELT HAPPY SO IT'S ALL GOOD!"
A few laughs sure... and yes... Todd Phillips is willing to include male genitalia in his comedy pallette but I hardly think that qualifies as "dark".
I give it a good solid C+.