Here's my beef. My slab-of-steak beef. The filmmakers objectively show the events of the inciting incident — the murder that puts the wife in jail — at the end. If the events had been left subjective and not justified Russell's actions, at least in our minds, I get the feeling the movie would have been that little bit stronger.
Here's another, sandwich-sized, beef. A tale of two Russells. The Jeffrey Wigand Russell, the passive, nervous, sweaty Russell. And the Maximus Russell, the incredibly competent, don't-fuck-with-Russell Russell. We get both Russells; the transition, whilst superficially plausible, is a stretch.