I was surprised by this movie - both positively and negatively.
The story was quite good and the cinematography was excellent. Idris Elba is a class act as always. Honestly the cinematography is the saving grace of this entire film.
That final showdown was a parody of westerns and gun showdowns in general - I was quite honestly laughing the entire time. One group who clearly took aiming lessons from the star wars empire troopers and the 'heroes' who never ran out of bullets and never had to aim. I'm not looking for complete believability, but that could have been done a lot better and had the same results.