It's an action movie. That's all you'll get, so don't expect more. They put a profession in the title because it implies the protagonist is a professional killer, but that's where the subtleties stop with this movie. "The Accountant" does the same thing, but holds that intrigue through the whole movie. With this one he's a bricklayer in the beginning and during one scene it comes in handy but for the rest he's just a CIA dude.
Aaron Eckhart does okay, as does Nina Dobrev, but what really holds this movie down is the lazy amateur writing. You can see the writer's hand in every single shot and things happen solely to get to the next action trope scene.
For example, this guy is a trained killer and in one scene he can take on 20 armed thugs in a row with practically little effort. But in another scene he GETS THE JUMP on one of the SAME guys and has to destroy half the room to take him out because it's the requisite one-on-one collateral damage "protagonist almost dies" fight scene.
There's a party where despite a giant fight including broken bottles and bodyslams, extras just keep dancing while visibly watching the fight because the writer wanted "a fight during a dance party". People are being tackled and punched and having bottles broken across their face and the dancers just keep dancing and watching like it's performance art. Only when someone pulls a gun and fires do people finally think maybe something is up.
There's a street fight during a protest against CIA interference in Europe (and who the hell is fighting FOR the CIA in that anyway?) and one of the literal CIA agent protagonists just walks through the middle of it without catching a single sideways look or errant punch.
The same fight and a nearby crowd are broken up by a murder in broad daylight, however seconds later the crowd is back together enough to block the escape of the very person who did said murder in broad daylight.
My point is, set your expectations appropriately. If you want anything to make sense, set them lower. If you just want to watch Aaron Eckhart beat people up and be all scary veteran CIA agent, bullseye.