There were some things that were changed from the comics, but I'll go into that later. It was very good. From the moment the opening logos appeared and the music started rolling, I knew I was going to like it. Now I'm not a huge Green Lantern fan, at least not of Hal Jordan, but comics are comics. I will admit that I didn't have too many high hopes at first, like when I first saw the cheesy suit, but after more and more trailers found their way online, I was convinced that it would be good. One thing I have to say is that Sinestro, his presence was just... amazing. I would have liked to have seen more character development for him before giving him the yellow ring, but some things just can't be changed. Some changes I don't mind, but if there were to be a sequel, I wouldn't want to rush just to see Hal and Sinestro battle.
One thing I will say about the movie is that some parts were definitely cheesy. Like for one, after Green Lantern rescues Carol Ferris, he randomly goes to her apartment and she somehow figures out his identity, which in the film was done in a funny way. Hector Hammond strangely had more screen time than GL, which kind of annoyed me. No one cared about him, he was a waste. Parallax was the only important villain in the film. At least he wasn't a pathetic cloud. Amanda Waller had a role in the film, one, which surprised me as I didn't expect to see her in a GL film. Perhaps there is something being established for a potential Justice League film. Maybe. I admired the constructs that Hal made with his ring especially when he was fighting Parallax towards the end of the film. The way he tricked Hector with the ring was also creative. I almost thought he gave Hector a fake ring. Close enough I suppose. Kilowog and Tomar Re were also awesome. Didn't do much, but then again the story was mostly about Hal and how he became a Green Lantern. Hal's relationship with Carol was a little stale, but then again that is most likely the fault of the writers. Some scenes felt like they were just jumbled together.
The action sequences were good. I expected a somewhat longer battle between Hal and Parallax, but there's only so much that can be done against an entity, which feeds on fear. So, in conclusion, i enjoyed the film and honestly I really don't understand why critics are bashing this film. If u don't read the comics obviously you're not going to understand what is going on. If u haven't seen it, see it now. Pray for a sequel. Oh, and be sure to stay after the credits, for a hint at a key scene that sets up the sequel pretty darn well.