Based on the chlorophyllous Lanterns from the DC comics house, the film was universally panned as a terrible adaptation. There may be a chance that it received a bit too much criticism. Closer evaluation should reveal that it is not much different from other superhero movies of its time. In fact, it does a few common things very differently from others.
Unlike other recent DC superhero movies, this one has none of the dark tones. In fact, it is a bit funny at times. The villains are cartoony due to the badly done CG and Ryan Reynolds is mostly himself in the film. It is much better balanced than recent DC adaptations like Man of Steel and Dawn of Justice.
After it is done setting up the Top Gun origin story, the movie quickens its pace. The Lantern’s love interest wastes no time in figuring out his real identity. It is a nice nod at the uselessness of the masks that superheroes rely on. Though her role promptly reverts to being the villain’s collateral.
The script is also willing to let powerful villains be killed by the sun’s heat and gravity. This is another minor departure from the traditional approach of getting slain at the hands of the hero.
Instead of fighting the hero, the two antagonists fight each other for screen time. I think it is the primary undoing of the plot. After spending a full hour establishing the origin of the superhero, any scriptwriter should’ve known to push the Parallax arc to a sequel. Instead it becomes a badly paced boss fight cramped in the last few minutes of the movie’s runtime. It fails to establish the immensity of the danger, which is already quite hard since all movies today have a similar scale.
Finally it also tries to squeeze in the Green Lantern council’s decision to forge a ring of fear. After all the lecturing on how fear is a very unpredictable force to place your bets on, this decision is so arbitrary and backwards that it singlehandedly justifies all the crazy backlash.
Blatantly ending with a post-credits sequence is the last straw.