What makes this movie great

When you hear a name like Rampage you instantly think of a bloody, hardcore shoot 'em up movie, which this definitely was but what I found to be the highlight of this movie was the dialogue and the interaction between the performers.
Uwe Boll's goal with this movie was to capture realism and with these aspects he nailed it beyond comparison. I've heard that the reason for this is because the actors improvised most of their dialogue, whether or not this true, idk but if it is, genius.