So I'll start this off by stating that I'm 23 years old, so this movie pre-dates me a bit, but nonetheless, I watched it for the first time tonight, in may of 2022, and I absolutely loved it!
I may be a little bit biased because I'm a pretty large Kevin Costner fan, but I genuinely had a very enjoyable time watching this film. The story and script were good and I can't wrap my head around some of these negative reviews.
Will Patton plays a phenomenal antagonist as usual and definitely gets the blood boiling throughout this film. The fight between Costner and Patton at the end gets quite a few complaints from people and I don't understand it. As Costner's character says himself, they're both "frauds".
The Postman is a great movie and is very enjoyable, all the actors do a wonderful job. I think most of the negative reviews come from people who don't have the attention span for movies that are barely getting started, when most movies are ending.
Give it a watch for yourself and form your own opinions. If you don't like it... oh well and if you like it (which you probably will), you'll be glad you gave it a shot. It's definitely one of my favorites now, but still can't beat Open Range for favorite Costner performance/film.