The only thing that really bugged me was one of the scenes with Tom. Yeah, overall Tom's fanboy-ness could be turned down a notch (it's an endearing quality, but not when it's shoved down our throats), but the one part that irked me, and forget exactly where it is...
...just looked it up. Page 29. Hal gives Tom "a lifetime supply of porn". It's like the "Sam's Happy Time" scene in Transformers. For the immature teenagers it might get a couple giggles, but for eveyone else (families, older siblings who brought younger siblings, dad's who are bringing their sons to see a character they grew up with come to life, etc.) it's just an awkward line that doesn't need to be there. Find some other way of Tom saying Hal owes him one.
Another thing, as has been pointed out before, is the villains. My issue isn't as much the way they're depicted, as much as it never seemed like one was the definitive main villain. Maybe show Legion in the beginning, Abin crashes, Hector touches the shard, goes nuts thinking he is all powerful, and the last 1/3 of the film has Legion heading to earth to regain it's missing piece. It sets up Hector sort of like Scarecrow in Batman Begins, still a villain who thinks he's all that, still a problem to be dealt with, but not the big problem by far. Just a part of the set-up who's too big for his briches. The final throwdown with Legion would be near/on earth, revealing the Lantern Corps to the humans and setting up for Alan's speech about aliens being real. (I don't know if that makes sense. I need to read the the script again)
The last thing I'm concerned for, and this in part relies on the actual film's FX, is the ring constructs. I want some crazy CREATIVITY. I don't just want to see a giant hand as the answer for everything. I don't just want to see the ring shooting blasts all the time. I'll have to look over the script again to see what they had in there again, but lazy creativity behind the constructs makes the difference between people thinking that the rings are the COOLEST HERO GADGETS EVER or saying "Dude, Batman's got better crap on his belt." I know Hal's just starting too, but it doesn't hurt to bust out something really cool from time to time. Once he figures out how it works, I could totally picture him just sitting up all night wondering what kinds of crap he can make and just waiting for a chance to bust it out. It doesn't have to be big either. Like in the new animated movie, there's a scene where Hal conjures up a folding chair and smacks people with it. That's creative. It's not huge, but it's not what you'd expect. It's spur of the moment. Was Hal watching Smackdown last night?
Other than those little nitpicks, I say it absolutely delivered. The interaction between Hal and Carol, the foreshadowing of Sinestro, and the hints leading up to the big payoff with Alan Scott, those things make this script go from good to great, and hopefully rewrites and better dialogue have only improved it. This could definitely be the Star Trek/Iron Man of 2011 with the right cast, FX, and killer marketing.