The acting in the film is good and not terrible at all. Ryan Reynolds is great as Hal Jordan and extremely likable. He definitely fits the role as Hal Jordan really well. Blake Lively is great and extremely sexy, she's not just a pretty face as most are suggesting. Peter Sarsgaard is a great actor and he plays the villainous Hector Hemmond really well and interesting. Overall everyone tries their best and at the end of the day do a really great job, certainly no Oscar worthy performances, though.
The special effects are pretty superb and extremely worthwhile to say the least. Although it sometimes feel a little CGIish, but it doesn't get too big of a distraction. I have to say I was a little disappointed how Parallax looked like, it felt a little fake at times, but it is not horrible in any sense of the way. Also the film did not take itself seriously which is kind of refreshing. Which could be the reason why critics disliked it so much. They want another sad, personal and serious story. Unlike Thor and X-Men, The Green Lantern is more kids friendly.
The main problem of the film was that they were trying to cram stuff in from the comics and the personal lives of the other characters. It seems that there could be so many sequels for the other characters. It did kind of focus on too many characters. Also the editing gets to be a little distracting at times, they certainly needed to have done a better job, but the editing is mediocre at best.
Overall the Green Lantern was a fun summer flick. Although it is nowhere near the realm of The Dark Knight, it didn't need to be. The 3D was actually really good and the special effects were memorable. No doubt, the critics were extremely tough on the Green Lantern and it is unfair. At the end of the day, don't listen to the critics. Make up your mind and see this film. At the end of the day, it should be only your opinion that matters to you. You might agree with the critics or you might not. However don't skip this movie because of the low Rotten Tomatoes score.