I can see why people don't like this.

It is the singular most depressing movie I've ever seen.

It's not like JFK where it pushes a theory. It just focuses on the death of the president and it's done in such a way that's designed to bring you to tears again and again.

I'm probably never going to watch this again, it's a little too much for me. But, if you are looking for a film that is going to invoke a visceral emotional response in the audience, than Parkland is the movie for you.