Unlimited is Unoriginal
The most striking thing to note about this issue is Joe Benitez's artwork, which is impactful in much the same way as a punch to the face. Simply put, Benitez' pencils just aren't very good. His knowledge of anatomy is questionable at best, he shifts between over- and under-rendering faces without ever finding a middle ground, and his sense of scale comes and goes from page to page. Ever woman has a twelve-inch waist and improbably long legs, and they seems to be stuck in a state of perpetual posturing, standing on tip-toes with backs arched and chests thrust out. Not to be outdone, the men in the comic scowl, grimace and glower, with the notable exceptions of the Joker (of course) and Superman, who seems to be the only character in the book uninterested in posing like a spandex-clad mannequin. In theory, "Justice League of America" should be one of DC's A-List books, and the title deserves a more polished artist than Benitez, especially when the reader is teased by Ian Churchill's impressive cover.
Comparatively, the story is better, but it also has some serious flaws. Opening up with a clever sequence in which Batman tries to escape a straight-jacket the Joker slapped on him, things steadily go downhill from there. Though the Leaguers initially treat their teammates' disappearance with due gravitas, within a few pages Green Lantern and Black Lightning are cracking jokes about Lightning's new haircut. It just feels wrong for the story, especially when it becomes clear the entire exchange was only there to shoehorn in a fourth wall-breaking joke about Lantern's redesign for the "Justice League Unlimited" cartoon. Also, while McDuffie tries to show the heroes and villains using their powers in new ways, it doesn't always make sense- there's an inventive spot where Poison Ivy incapacitates Green Lantern by using her powers to multiply the bacteria in his digestive tract, which only works until you remember from ninth grade biology class that bacterial life isn't the same as plant life. By being so specific in describing what Ivy is doing- right down to naming the bacteria she's affecting, and the possible medical side effects- McDuffie inadvertently makes the scene much less effective than if he had left a few things to the reader's imagination.
The biggest problem with this comic, and the entire "Unlimited" storyline is that the idea of Lex Luthor gathering an army of super villains together had just been done two years earlier. The creation of The Society was a huge part of DC's "Infinite Crisis" crossover, and the Society's influence was felt in the pages of nearly every one of the DCU's books. While the Luthor who formed the Society was actually Earth 3's Alexander Luthor, not lovable Lex, this story still reeks of a rehash.
