Although Star Trek takes place in the future, this thing is so seventies it's not even funny.
Scratch that: it's so seventies it's hilarious.
From the amazing outfits, to the classic hand-drawn scene settings, to the Epcot-like depiction of Starfleet HQ, the film paints a very specific picture of mankind's utopian future. You might find it outdated, but we find it downright charming.
In a similar way, the filmmaking style is very much rooted in its era. We're talking mostly practical special effects. We're talking the occasional use of soft focus. We're even talking about the tempo of the film, which would be considered glacial by modern standards. Though these might seem like criticisms, they're actually the reasons we like the movie. It's like a time machine that works in both directions simultaneously.