I agree the movie was ok, maybe even above average.
I think it's probably very hard to make a good comic book adaptation into a good movie. There is so much ground to cover and so little time in one 2 to 2 1/2 hour movie. You have to give character background of both the hero and villain. Then there's the origins; how they become the hero/villain. Next is why they are enemies. Etc, etc.
It's also hard to please everyone in a comic book movie. Stick right to the comic and please the hard-core fans, but lose the non-comic readers. Fail to explain the origin, and you piss off the comic nerds. You have to find the right balance to appeal to a wide enough audience to make the film a success.