For a movie about a guy with powers only limited by his imagination, I found Green Lanterns powers very unimaginative.
It had all the right elements to it, except one vital thing: They didn’t beat up Hal Jordan enough. He was never in any real danger, and this made it boring. Any superhero movie that doesn’t spend a good 5/6’s of the movie beating up the main character just isn’t interesting. Some of the lighting was really bad too.
Other than that, it was a decent movie and would make a great rental, it just wasn’t home run like Spiderman or Transformers.