The reviews saying it's 'unrealistic' kind of miss the point as the film isnt taking itself too seriously. The characters arent fleshed out too much, which means the deaths arent all that sad, but I actually found that to be a good thing. It's very well cast and the acting is brilliant, there are many character flaws too which give the audience a nice insight despite the short run time. It's very entertaining- I didn't find myself reaching for my phone at all. Not to mention, I found myself laughing many times, mainly at the characters. It's silly and fun and a good action film. Bits felt rushed and there are some plot holes for sure- but none of these things spoiled the film for me. There is also some social commentary which did feel a little out of place in a film that is not very serious, but it's not bad.
Overall, I have a feeling the bad reviews are not from its target audience. Give it a watch, I say, I would definitely watch it again :)