Fear vs. Courage
Green Lantern was not the best comic book movie that I've seen. But it was one of the better ones. I'll skip past the action and CGI (excellent, as usual), and focus on what made Green Lantern stand out from other comic book films.
First, there's the whole discussion surrounding fear. In the real world, if someone says they are fearless, they are either lying or crazy. Had Hal simply put up a facade of fearlessness, Parallax would have crushed him. True courage comes from being able to ignore fear. And that's what makes Hal Jordan so powerful.
The other thing was the romance plotline. Everyone knows that the guy gets the girl, so Green Lantern never pretended anything else. In fact, having that history between Hal and Carol gave them the rapport necessary for Carol to help Hal realize his true potential (see above), something a new love interest could not have done.