I honestly don't know why the movie received such low scores. It seems like a combination of people expecting it to be more of a fast-paced action film or people offended/turned off by the gay element/subplot of the film. That kind of ignorance in 2019 is really quite discouraging.
For a more objective perspective, keep in mind this in an independent film that's much more of a character study than some sort of heist film. One reviewer drew a parallel to Brokeback Mountain, and there are definitely similarities - specifically that love and sexuality can be fluid and even confusing, and more importantly that one can't chose whom they love. However, it's not a rip-off of Brokeback Mountain; in fact I believe it's loosely based on real people & events. In doing so, it's also a look into a person's nature and If they can change or if they're doomed to repeat the past they know.
So, no, it's not some glossy big budget Hollywood fare, but it's a solid film with some honestly sincere performances - I was really quite impressed w Sullivan Stapleton (showing range I've not seen before). I may have given it a higher rating than it deserves (it may be closer to a 7), but that was partially to offset the unfairly low ratings.
Bottom line: If you're looking for an action flick, then skip it, but if you enjoy well crafted character driven films (that may take a different approach to story telling than American audiences are accustomed to), then give the film a chance.