For me, this is an instant cult classic. IMO, character development is the most crucial aspect of each story, & this story's characters are categorically convincing, as well as satisfying. Coincidingly, the storyline, setting, etc., complement the characters' performances to provide us with a truly memorable rush.
Then there are the treats as they surprise us with a few "Easter Eggs" along the way. (Those are so much fun!) They add depth & give us a way to connect (like an "inside" joke or secret).
Though "Invasion of the Body Snatchers" & even R.A. Heinlein's "Puppet Masters" weren't entirely Easter Eggs, we can imagine similar stories like, "The Thing," (with Kurt Russell)... Loss of perspective (worsened by fear), body horror & favoring the social outsider: Nerd (Casey) & Helicopter Pilot (McCready) as the Protagonists. LOVE THIS. 🥰
Then there are more subtle surprises: Principal Drake & the Drake equation, which represents the number of possible intelligent alien lifeforms in our galaxy. (My inner nerd loves this, too.) 🤓