These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ensemble Darkhorse: Ducky, despite being simply a supporting cast member, is considered by many to be the most memorable character in the film.
Fan-Preferred Couple: An interesting example; the test audience disliked the original ending, where Andie ended up with Ducky, because they felt it created a Broken Aesop about not crossing class lines (which was arguably what the film was about). When the film was released, it had a new ending in which Andie ended up with Blaine, but this was also met with a poor reaction, and Ducky/Andie has been a Fan-Preferred Couple ever since.
Stoic Woobie: Andie is this when you consider the fact that her mother left the family and that she always knew her mother didn't love them. SINCE SHE WAS FIVE.
Unintentional Period Piece: Even by 1980s teen dramedy standards, this is pretty damn 80s. So much that if people showed up dressed like these people in a movie today, the audience would assume the characters were satirizing the 80s. There's also a lot of Duckie's dialogue (such as him saying "bogus" unironically).