For my purposes, there are two major plot twists in the Star Wars universe:
- Vader: "No, I am your father." (The Empire Strikes Back)
- Luke: "My...sister has it." (Return of the Jedi)
This is completely disregarding the prequels' twist, which is "George Lucas completely lost his mind."
One of the two main twists works, and one doesn't. Vader's revelation to Luke is, obviously, classic. It adds a bit of weight to the remainder of the series' installments, and has implications that completely change the main character. Luke goes to what seems like a darker place and comes out seemingly more mature. He learns from his father's mistakes and avoids the lure of the dark side, even becoming willing to sacrifice his own life for the light side. It certainly merits its place in the second spot on the Premiere Magazine list.
The latter twist is a bit of a cop-out. They needed an easy out to resolve the Luke-Leia-Han love triangle, so they made Luke and Leia siblings, completely disregarding common sense in favor of an ending that is completely happy for everybody (including the rock-slinging teddy bears).
But why does one work more than the other? Simple. There's background to Luke's father. We know there's a father missing. The stage was set during the original Star Wars and throughout Empire. Film viewers love mysteries, and a successful twist will make somebody want to look back on the earlier clues to put the pieces together.
With the exception of the Yoda's hint that "there is another" in Empire, there is no inkling that Leia could possibly be Luke's sister. Nobody has ever mentioned another Skywalker sibling, or that Leia was adopted. It all seems lame and--to speak in cliché--deus ex machina. It would have added major character depth to Luke to have him give up Leia as he moved on to a much different life.
See? I don't unquestioningly watch the Star Wars movies, despite the fact that I *cough* own toys.
There's a reason that everybody went back again and again to see M. Night Shyamalan's The Sixth Sense. It made sense! The whole thing was tightly composed and intricate enough to detail a scenario that was probably not in the viewer's mind in the least. Even Night's later, meh-ier movies like The Village and Lady in the Water laid stepping stones to whatever bizarre twist came next.
It's not a twist if it doesn't make sense. It's just a weird surprise. It's like having the Scream killer remove his mask, only to find Alex Trebek underneath. Where did Trebek come from? Is it the mustachioed Trebek or the post-9/11 baldface? Always remember and never forget.
Where did the point of this post go? Oh, maybe that's it over there.