I was surprised that Die Hard, which I used to claim as a masterpiece, is still engaging today, and that's rare for any other movie that ever was a childhood favorite. It probably is among the most influential ever action movies and seems to have invented a few cliches of its own, like the punching of some annoying character at the end of a movie or the silly and noisy police chief (no research done on these). There's loads of good humor, some which is easily-missed (FBI having a laugh), and some on the surface, like the amazing confidence those FBI agents portray, not to mention the idiocy clearly shown by their silly faces.
My favorite characters haven't diminished their charm (the police who repeatedly converses with the hero over CB radio, the limo driver, and most notably, the computer cracker. Bruce Willis' shouldn't be left out either for his amazing charisma.
This, together with the second sequel, Die Hard With A Vengeance as well as Predator, made me honor John McTiernan (who directed them) as the greatest action movie director ever, and that honor should probably stay there for there haven't been much great action movies recently.