I've seen these movies when I was... 18 ;_;
Unfortunately, I didn't do my homework, so I saw the new trilogy first. After that, the old trilogy seemed funny. Absolutely awesome, but funny.
My most favourite aspect about the original trilogy is Yoda (the muppet)! Watching his ears swing around while he babbled wise inverted sentences is just awesome >.<
Next are the droids. R2 is exploratory and adventurous, while C3PO is always whining about R2's "rash behavior", but still follows him around. ("Oh dear! I know I'm going to regret this!")
Then the main characters: Luke, Ben (Obiwan), Han, Chewbaca, Leia, Lando...
Finally: VADER!!! OMG! I feel very bad for missing the real Vader, but he was anything but scary. Every time I saw Vader, I couldn't help smiling and sometimes laughing. I just love him! I keep giving quotes to my unaware friends and they are like: "...wtf :?" lol!
PS: "Search your feelings, you know it to be true!"