Green Lantern was a fine movie. I loved it. It didn't take itself too seriously, and it was the perfect film for its (assumed) target audience: kids. By no means was this an "adult" movie, yet it's adults (adult fans, adult critics) who are hating on it. It seems invalid to me. I feel like the movie is "good" by default. Isn't that all we ask - that it be good? Everything needs to reach this Dark Knight / Avengers level now, which means those two movies pretty much killed the genre.
This is my whole problem with comic book films, and I have to throw a little blame at Nolan, even though he did nothing wrong himself; he just kind of spoiled the adult comic book fans. I was 10 years old when Batman & Robin came out (1997), and I thought it was the coolest damn thing on the planet. All of my friends were rattled by it, and were foaming out the mouths over Schumacher's two films. Imagine me, a 10 year old boy who loved Batman, sitting in the theater next to a 35 year old, and the 35 year old says, "This movie SUCKS! Worst movie EVER!" What gives him the right to say that? The answer is: Nothing. The movie wasn't for him, just like Green Lantern wasn't entirely for us.