I have mixed feelings about his work, but Mark Millar has a gift at crafting comic book properties that translate to the big screen (Wanted and Kick Ass being two examples). Here he gives his opinion on the possible challenges of a Justice League of America movie featuring superheroes with a long legacy tracking back to the early woolier days of comics when a feller could look goofy, fight silly villains in a four-colored fantasy world.

In my opinion, the strength of the DC Universe is in its fantastic nature (though the current Batman monthly titles feature the Joker literally wearing his own face like a mask, held in place by a belt). Like many, Millar's approach seems to be similar to the one taken for the Avengers, Watchmen and even the Dark Knight Trilogy in which a comic book reality is translated into the real world. Personally I think that is a mis-step and can only hamper the success of a feature film focusing on colorful characters with larger than life personalities and abilities that seem more at home in children's adventure stories than a gritty action drama.
JUSTICE LEAGUE OF AMERICA_200_George Perez
Sure, you can make a grim crime fighter hard-edged and sophisticated but how can you turn the same trick with an amazon princess, the fastest man alive, the king of the seven seas and a galactic cop with a magic ring? A much better approach would be to embrace the silliness and weirdness of it all rather than try to make sense of it.

Millar specific worries...

(Via Bleedingcool)

Speaking to Sci-Fi Now, Millar outlined some reasons that he thinks a Justice League adaptation wouldn't cut it at all.

His first, general complaint is that the characters are old:

The characters were created 75 years ago, even the newest major character was created 68 years ago, so they're in a really weird time…

So far, I don't follow him, but he does have character-specific worries too. Here he is on Green Lantern:

His power is that he manifests green plasma from his imagination and uses them as weapons against someone? Even that in itself if you just imagine then watching a fight scene with a guy who's like a hundred feet away making plasma manifestations fight someone – it's not exactly raucous, getting up close and personal.

Okay, not a terrible observation but far from a deal breaker. And then, slightly less well-argued are his points against The Flash:

The Flash has door handles on the side of his mask and if he doesn't wear that mask, I'll be pissed off, you know what I mean? They're in a weird, weird situation – if you've got a guy who moves at the speed of light up against the Weather Wizard and Captain Cold or whatever, then your movie's over in two seconds.

Door handles.

Millar is also rather worried about Aquaman's ability to communicate in his native environment:

Aquaman can't even talk under water. If you think about it in comics it's fine, you just have a speech balloon, but how do you have Atlantis and people talking under water? Are they gonna talking telepathically? Is it going to be body forms?

There's not an insurmountable problem in the lot. In fact, all of these obstacles are easily soluble.

Still, Millar hammers his point home by slamming the whole combination:

The actual logistics of each member of the Justice League is disastrous, and you put them all together and I think you get an excellent way of losing $200 million.

Over at Fox, Millar is nurturing a shared comic book movie universe. That one will blend The X-Men, The Fantastic Four, Deadpool and, very possibly, a few other stragglers that can be pulled in from the peripheries of the X and 4 universes. He's got a lot of odd problems and legacy quirks to work with too.

ff-x-men

I may be late to the party here, but is there really a plan to develop a shared universe between the X-Men and the Fantastic Four?? I know that Sony and Disney want Spider-Man to cross into the Marvel Avengers Universe, but tapping the potential of the Fox-owned properties is very interesting.

Of course a lot rides on the success of the mysterious Fantastic Four reboot and the Days of Future Past X-Men flick from fan favorite director Brian Singer, but if both of those projects work, we may be seeing a lot more comic book movie madness in the near future (and that's already anticipating the Avengers sequels, Ant Man and Doctor Strange!).