How bad you think Green Lantern is will depend on how much leeway you want to give the crew involved... What mean by that is; when I watched Green Lantern I, being a fan of DC, wanted them to do well so I gave them some credit for trying... And was still disappointed. The mistake they made was instead of JUST dealing with Hal Jordan's origin story (and leave the rest for sequels) they tried to cram in that plus the history of the Green Lantern Corps, The Guardians of OA, Parallax, Sinistro's origin and decent, Earth's place in the galaxy, etc. As if you can cram 40 years of history into two hours.
A lot of people forget that "less is more." If they had just kept it simple and deal with Hal on Earth learning his powers and fighting an earth bound villain or two, they could have ended it with him being summoned to Oa and meeting the Corps... Tune in next time for more adventures of The Green Lantern! Origin story first, then you can just tell good stories taken from/inspired by that character's books.
That's a similar complaint to the one I have about the upcoming Spiderman and Superman reboots; WHY DO ANOTHER ORIGIN STORY?! Spidey is bitten by a spider, Supes is from Krypton, we KNOW! Both of those characters have had their origins portrayed numerous times in multiple mediums. Now just tell a good story and stop putting in the kitchen sink every damn time.
I'm starting to rant. Sorry.
I'd love to see the Blackhawk comics adapted into film... But for now we may have already gotten as close as we can, stylized though it may be:Sky Captain and the World of Tomorrow