Form - For such a pulpy seventies film, Star Wars manages to keep all the action exciting and well-paced.
F/X - Crazy! Models galore, stop-motion marvels, everything that makes special effects great rolled up into one.
Acting - There's a good reason why a lot of the actors from the original Star Wars trilogy never did anything with their career: they're only good in the ridiculous space opera schlock. Still, it's great schlock.
Mise en scene - Invents its own world masterfully, borrowing heavily from early sci-fi classics.
Quotables - Countless. "I've got a bad feeling about this", "Use the force Luke". Practically the whole script is one long, long quotable.
Cool stuff - Everything.