Let's just all agree the the recent Green Lantern movie wasn't what we expected. We all expected a great comic book movie, what we got was a comic book movie that was more like Batman & Robin than The Dark Knight.
I will say this though, Green Lantern was visually stunning. The constructs looked amazing, and the Green Lantern Corps looked incredible.
That being said, the Green Lantern movie was corny. Really corny. Whether is be the scene with Hal's kid nephew or the flashback of when Hal's father threw his coat to his son before he died (in black and white, I might add) the movie was filled with cliches.
Despite all this, I think a sequel to Green Lantern could be amazing. The biggest problem with DC characters, with the exception of Batman, is that their origins aren't as down to Earth as Marvel characters. With Marvel, for the most part, you have things that can be explained through science, like Iron Man's armor or Captain America's serum.
DC however, is much more fantasy-based. You have more aliens from another world and magic rings from space than high tech armor. With those fantasy elements, the origins can be a little campy, especially when they are put on screen.
I feel, however, that once you get the origins out of the way, you can really get into the great story telling. With Green Lantern, you can get into the Sinestro War Corps or Hal being possessed by Parallax. You have all these opportunities that really weren't available in the origin story.
A Green Lantern sequel has much more potential than a Green Lantern origin. Now that they don't have to show the corny black and white flashbacks or have the voice-overs that start out with the phrase, "Billions of years ago..." Green Lantern can go on the be the bad-ass movie franchise that it is meant to be.