This movie is so good. I can see why it appealed to me as a teenager. There's this wonderful running theme about stepping up and saying the truth (including authentic feelings) in this buttoned down society that is always trying to paper over everything. There is also a running thing with repression of the arts and sciences when they don't fit this papered over reality.
I never tried to unpack the dimensional time travel stuff that much; I liked the movie for the sort of things I mentioned above, there's an almost philosophical bent to it at times. The time travel stuff is probably the least interesting part of the movie. It was the perfect movie for it's time which naturally (if coincidentally) meant that it had to stay buried for a bit before anyone saw it. I would say this movie was of it's time in the best way.
I still love Donnie Darko even though I'm in my mid-50's.
I love the way it makes me feel when I watch it. There's this sweet dreamy sense of loneliness and longing and a semi-bittersweet ending that somehow still feels positive but sad especially considering the last frames. It's like the words "Cellar Door," they just roll off your tongue with such grace and ease and also feel mysterious.
I like how raw some of it is, emotionally.
I like that it is so damn quotable. Like, SO many freaking lines can be quoted from that film, not just the quirky funny ones. ("I'm beginning to doubt your commitment to Sparklemotion!" or that whole conversation around "fuck-ass" at the dinner table in the beginning, that STILL makes me laugh.) But also, "Every living creature dies alone." It's profound in its simplicity -- and that the search for God seems so meaningless if we die alone no matter what. That's not the only insightful line, it just seems peppered with them.
I like how it has so many cast members that went on to become much bigger names or were names. The Gyllenhaal's. Seth Rogan. Jenna Malone. Daveigh Chase. Jolene Purdy. And people who were already known like Patrick Swayze, Mary McDonnell, Katharine Ross, Beth Grant, Holmes Osborne, Noah Wyle, Drew Barrymore.
I like the original version better than the director's cut overall, which picks an interpretation for you and explains too much (IMO). I really like how the original cut leaves it unclear how much is science fiction vs Donnie's psychosis.
I like that it has a better cover of a Tears for Fears song than the original version.
And I really love the scene where Donnie is feeling so lost and alone on his bed, and he asks his mother, "How's it feel to have a wacko as a son?" and despite the gulf and friction between them, Mary McDonnell just puts her hand on his shoulder and says with such gentle love and affection and in total sincerity, "it feels wonderful." it is one of the best line deliveries in a film I've ever heard in my life and I will never forget it or how it made me feel to hear it.
Honestly, despite all the cool time trappings, it's a film more about how it feels to be lost and alone and somehow finding not just peace but feeling like even with inevitable loss at hand like you still have a place and you belong.