Seen it before? Oh yeah.
It's more highly regarded by many than the first one, and rated higher up on the list. It's slower and talkier than the first one. There's more philosophy here; the Yoda scenes are sort of like Zen Buddhism For Dummies. Vader is a total badass in this movie. Blackest brother in the Galaxy. Nubian god. It seems like the worst thing he can do is give you a promotion. The last half-hour with Han getting frozen, Luke and Vader's duel, and the famous reveal (that always gets misquoted. he doesn't say "Luke, I am your father*") is basically pure awesome.
Nevertheless, Empire Strikes Back has some problems:
*That was a spoiler. If you have not seen Empire Strikes Back, you should not have read that sentence.
Position on the list: 10
Adventure, excitement? A Jedi craves not these things.