The term for Mechanic here does not mean one who uses tools to repair cars or other form of machinery. It has a more sinister meaning to it. The Mechanic refers assassins who fix problem through killing people and Arthur Bishop ( Jason Statham ) is one of the best "mechanic" around. Arthur's method would be to make the assassination look like an accident. In his own words, the best jobs are the one that no one even knows that you are there.
Jason Statham look like he is just right fit for the role of a meticulous assassin. His tough demeanor helps to build a credible determination to carry out the task in any extreme circumstances. He also build a career playing professionals who are at the top of it's field (eg. The Transporter series). The opening sequence of Arthur Bishop performing a secretive assassination of a heavily drug lord was pretty good and we are off to a good start.
Then the movie introduced Harry McKenna (Donald Sutherland) and his son, Steve McKenna (Ben Foster) into the mix. Harry was Arthur's contact in the hitman agency and probably one of the few real friends that Arthur has in his line of work. Steve is the wayward son who couldn't hold down his job due to his disruptive behavior. After Harry's apparent death in a carjacking incident, Steve started to randomly hunt down carjackers in a desperate bid to avenge his father's death. Arthur reluctantly took Steve under his wings and trained him as an assassin. The catch here is that Arthur is holding onto a secret that is detrimental to his new partnership.
Ben Foster brings a sinister aura to his character as the apprentice with a grudge. It was fun to watch his character cutting loose as a wild cannon. It brings an entertaining contrast to Arthur Bishop's cool restrain killer with a secret to keep. It was also engaging to find out if Steve managed to find out the secret that Arthur has been keeping from him and what sort of actions would he take.
But once Steve appeared, the movie changed it's tone and abandon the meticulous killer's stealthy assassination angle. It was filled with loud gunfights, explosion and devastating fights. The type of loud mindless movies that would satisfy the general action flicks goer. With the increase focus on one action setup to the next, the plot gets progressively dumb down. Arthur conveniently found out that he had be betrayed by his agency and Steve conveniently found out the truth behind his dad's death.
Another problem with this movie would be how morally righteous with the protagonist. All the assassinated subjects are immoral individuals that could be the antagonist in a movie of their own. It takes away a certain ambiguity of a killer's moral stance and that made Arthur's character a little too bland. This movie would also benefit from removing the numerous assassination in this movie to focus on Steve's training to be a professional hitman or the rising conflicts between them.