I have seen it twice - and to be honest, my "seeing movies twice" days are mostly over! - and loved it both times. It was funny, and FUN, and the action sequences were great - what do you know, there ARE folks left in Hollywood who can choreograph a fight scene so you can actually FOLLOW what is happening, even at tremendous speed! Hit Girl's two sequences are amazing, and while Big-Daddy's warehouse attack is short, it is fantastic. And while the movie pokes some fun at superhero conventions, it also delivers some of the best superhero fun I have seen on-screen in a long long time.
I am a BIT surprised at the relatively low box office. I am sure the R rating doesnt help in that regard.
Shadow
PS - I should add, never read the comic, so I took the movie "as is"...which may or may not have influenced my perspective. Frankly, loved the tone..and from what i have HEARD of the comic's ending, think the movie ending worked a lot better for me.