I'm going to rhapsodize a bit about Die Hard because I've given some thought as to why it's a "perfect action film".
As a point of background, my Dad took my brother and I to see it in the theater days after already seeing it with my Mom (you could get into R movies with a parent). I guess he figured we'd be more appreciative.
1. John McClane is a blue-collar every man hero.
-He gets the crap kicked out of him in every possible way. His fights are not easy, but hard. He struggles against individuals one on one and wins through sheer determination or luck and grit as opposed to sublime combat skills.
-He also manages to always say the most appropriately comic thing at the most appropriate time, in a way that everyone wishes they could.
2. The opposition is formidable.
-It is established early how professional and dangerous the terrorists are, when it comes to their planning, their weaponry and their general disposition. It adds to the tension because being outnumbered by these guys appears to be a significant obstacle.
-Also, they are distinct individuals with names and dress. These aren't endless masked thugs but members of an actual team with roles and responsibilities. You can sort of follow along with McClane as he works his way through the opposition.
3. The support by law enforcement is pathetic and hilarious to the point of absurdity.
-John can never rely on or be seen to require the help of the outside. Not only that, they even actively work against him (in terms of the chopper) and are never appreciative of his efforts. It magnifies the sense of isolation and his challenge.
-Law enforcement also serves as an additional source of comic relief: from Agent Johnson and Special Agent Johnson (not related), to Deputy Chief Duane T. Robinson getting *******ed on national TV, to the SWAT guy pricking his finger on a flower in a rose garden.
4. The primary villain is compelling.
-This might be the most important element. Hans Gruber eats up screen time and is arguably as entertaining as John McClane is. Stylish, debonair, you're almost rooting for him by the end of the film.
-Karl provides intimidating and effective back-up.
5. Strong support characters who keep things light.
-The film does a good job of providing entertaining scenes to a wide range of support characters, from his wife (What idiot put you in charge? You did, when you murdered my boss.), to Argyle the limousine driver, to Theo the amusing computer expert, to Al Powell as the only emotional lifeline he has.
-What about Ellis? The guy that is such a douche that you don't actually mind when Hans shoots him? (Hans, BOOBIE, I'm your white knight! Maybe it's the heebs, maybe it's the camel jockeys...)
-The reporter subplot is a lot of screen time for a sidequest but provides additional elements of comedy at the expense of the media (including the scummy reporter Richard Thornburg and the idiot anchorman).
-The characters manage to be distinctive and memorable without a lot of exposition required.
6. Pacing is excellent.
-For an action movie, it does an admirable job of pacing, from breath-taking stunts and firefights to lulls that provide interactions among the terrorists, the terrific scene where Alan Rickman uses his American accent, to Al and John having their bromance moment.
7. It's still a bit of a time capsule.
-As an older person, the movie doesn't seem that old to me, but there are obvious reminders like the lack of cellular phones and Holly informing her pregnant assistant that having some champagne is ok because "that baby is ready to tend bar".
8. When I say it's perfect...
-Well, obviously it's not really perfect. Beyond the obvious plot holes or mechanisms to delay the conclusion of the film, there are a few elements that to me, even today seem a bit out of place.
-Karl coming back to life just in time for Al to get over his fear of shooting people seemed tacked on and a bit gratuitous.
-The FBI seemed unusually bloodthirsty for no particular reason.
-John spends hours in the building and kills many terrorists but never finds a pair of shoes.
Overall though, it's a movie that I never really tire of, which is surprising.