"The Beast" as the title translates, doesn't really ring true.
Akin to films like "Taken" (which is also implausible) the primary issue with this film is one of realism. The key protagonist is apparently a highly skilled, special forces operative. Yet his situational awareness is poor, as is his judgement. Of course, we are told he has PTSD. Even so, that level of experience becomes instinctive, so this is a thin excuse.
He blunders into multiple hostile situations. His combat skills look more like those of a simplistic street fighter. They lack polish and precision. No one with that kind of background would go in unarmed, either. A hammer, a box cutter, kitchen knife, or even a crow bar, can make a huge difference.
Just as improbable, his adversaries leave him for dead at one point, rather than finishing him off. All this after he proves he is at the least a tangible, if disorganised, threat.
Acting by contrast, is excellent. The main character is believable but he's let down by a script that fails to seriously ask how a soldier with this degree of training and experience, would really perform in this kind of scenario.
The outcome is a film that's more or less watchable but for anyone with any real training, it offer's up far too many "yeah right' moments to be convincing.
5/10 from me.