What it comes down to is this: Green Lantern has flaws. Copious, egregious, obvious flaws.Dude go see it, it's honestly not as bad as Bob says I was expecting it to be bad but I really enjoyed it. I think a lot of these reviews came from people who decided not to like it before watching or who are biased against Ryan Reynolds.
That said, if you enjoyed the movie anyway? More power to you. But just because you liked it in spite of its problems, doesn't mean those problems aren't there. It's just that you're able to look past them. Other viewers may not.