Well, there's a third of a great movie here--the bits dealing with the Green Lantern mythos, which are given appropriately mythic and epic feelings. How successful these bits work for you depends on your tolerance for excessive CGI (which really, y'all might as well admit that battle was lost long ago) Those bits work without question, much like how Thor did a great job of selling Asgard as this amazing place.
There's also a cool wrinkle they added that almost--almost--makes Parallax work. Unfortunately, the choice to portray Parallax as an evil cloud doesn't work very well. I would have hoped after the second Fantastic Four movie that people would twig on the idea that evil clouds make rather silly arch-enemies, but maybe next movie.
The problem is the other two thirds--the Hal bits are Top Gun with the names changed (seriously, they barely bothered to change some of those beats) and the rest is Campbell-cum-Star Wars Hero's Journey boilerplate, with a side helping of daddy issues that are supposed to give our hero and villain some gravitas, but it fails to.
However, I have often said that typically I like everything about Green Lantern apart from Hal Jordan, so really, the makers of this film have managed to transfer the experience of reading the comic with frightening accuracy, when you get down to it.