The dark comedic undertones of the film definitely scream Coen Brothers at you, which the film had a sort of comedic undertone throughout the whole thing; crushing pills with a roller, the bike ride, eating the drugged meal without a clue, etc. They worked well.
What didn't work well was the tie in with the black family. It almost had no relation to the plot. If there was a intention of making a statement on racial discrimination in White Picket Fence Suburban American, they missed the target.
Oscar Issac carried this film on his shoulders. As soon as he came in, Boom. The movie just started. His wit and cleverness, while playing on the characters was smart, and definitely a Coen brothers character. His character gave the film the boost it needed.
Also, Matt Damon plays the role he does best: Being a Scumbag.