There are certain topics, that a lot of film makers avoid, because either its physically to complicated to set up rules and explain them, or they fear the possible backlash. This is why it's even more refreshing to see this approach back in cinema again.
While the movie doesn't reinvent the wheel, it is an absolute joy to watch and you are not being held back from enjoying the plot by wondering about the specific mechanics about "how does this actually work?" (Without going into spoilers to much, just see it for yourself!)
Jamie Dornan and Anthony Mackie have an authentic and gripping buddy relationship and both of them should be happy to have signed up for this script. I even struggle to put this movie into a genre, because there is no "Buddy-Thriller-Scifi-Horror-Dramady" category. This movie is weird in the most positive sense of the word and should be enjoyed without reading any spoilers ahead, hence this style of review.
The budget for this movie wasn't massive, but due to a fantastic piece of cinematography work, it looks much more expensive and just beautifully well done!
Yes, money is important in this industry, but here we have a stunning example what can be done with dedication and creativity!