I saw it a couple days ago. Hal Gordon sort of exists as a 'non-character' in this movie, I actually think they'd have been better off with John Stewart as the lead character (don't know much about GL comics, but JS is much cooler in the JL toon than Hal is here). I don't really get Hal Gordon. Is he a cast off from top gun? A quitter? A underdog? An overdog?
It's never really made quite clear how his personal history informs on his superhero creed (in comparsion to Spider-Man, Batman, Superman, Iron Man, etc. who's motivation are easy to understand).
If the lead character fails, the movie fails.
The romance was painful. The romance in Thor was under written, but the the chemistry is undeniable. That's where casting can make a big difference.