Spoilers.
I liked the acting.
Marla, played by Pike, is more ruthless than the mob boss Roman played by Dinklage. That's why Roman decides to go into business with Marla because the people who work for him are incompetent.
Pike plays a convincingly evil person named Marla. I, unfortunately, have met people like her; they do have this predator/prey mentality. Pike's character has dehumanized the old people. She only loves her partner showing that even evil people can care about someone but that it doesn't deter from their crimes.
Dinklage plays a greedy mob boss named Roman who goes Dr. Evil when killing Pike. He puts her in an apparently easily escapable situation, turns his back, and hopes everything goes to plan. Then he puts his feelings aside to go into business with her showing that he loves money most. He has this strange sense of loyalty and honor among theives thing going on with Pike's character (Marla). It would have been better if he betrayed Marla once he got his mom back. He adored his mom and Marla made her suffer. Wouldn't his mom have expected pay back too?
Dinklage was scary when dealing with the first minion; I thought he was going to literally shoot the messenger, but instead he let the minion screw up some more. The scene where the first minion gets hooded and bonked with a bat had a Three Stooges feel. Note: I didn't want the minion killed. But I did want to see a successful escape.
Weist who played Dinklage's mom made this movie better. She also played Virginia's mom in 'The Tenth Kingdom'; doesn't this woman age? Anyway, her acting was exquisite. She was tough as nails and should have been the mob boss. If she was it would explain why Roman was struggling to lead his crew; he was still learning the ropes. I really wanted to see a battle of wits between her and Marla that ended with Weist's character serving up a helping of justice.