The Martian Manhunter comes to Earth to warn us that an unknown race of aliens, the same ones who wiped out all life on Mars (except him) are now coming to invade Earth. The Manhunter is intercepted by our government and imprisoned in a government facility, but is rescued by Superman and Batman, who then set out to battle the aliens. Other heroes (Flash, Green Lantern, and Hawkgirl) show up to assist, while Princess Diana decides to leave her home island of Themyscria to help save the Earth. The united heroes save the day, and then Bruce Wayne uses his fortune to have a giant watchtower satellite built in space that will spot any further incoming cosmic threats to the Earth. The other heroes decide to band together and use this tower as their base of operations, while Batman elects to wait on call duty.
Most of these characters have already been introduced (I assume) in either the Superman Adventures or Batman Adventures cartoon series, so the only two origins presented here are Martian Manhunter's, and Wonder Woman's. Martian Manhunter's origin was simplified from his comic book equivalent, but for the purposes of this cartoon series, it's probably for the better. Wonder Woman's origin seemed rushed; her motivations murky and the legacy of her equipment unexplained. Also, it was really odd having her portrayed as the unproven rookie of the team, especially next to the much less iconic Hawkgirl. For that matter, I found it odd that Hawkgirl is on the team at all, since she's basically just a female counterpart to Hawkman. I mean, if they want to make her a character on her own, shouldn't they at least change her name to Hawk Woman?
Using aliens, especially shape changing aliens with a vendetta against Martian Manhunter, to bring the Justice League together is a good idea. I have to confess, though, that I was really disappointed when I realized that they wern't the White Martians from the Grant Morrsion comics. It would have been a logical way to start off the series, and the Watchtower could have been built using White Martian technology, the way it was in the comics. Isn't it kind of odd that Batman funded the tower if he doesn't want to be part of the team? I sincerely hope this was done on purpose, like Batman is suspicious of Wonder Woman and the Manhunter and wants to keep an eye on them, as opposed to just being an oversight by the creators. Also, even though I've heard him say it a thousand times, it always kills me whenever Batman somberly informs the League that he's just not a team player. Despite the fact he's one half of the most famous duo in comics, or that he has a larger "hero family" then any other member in the Leauge.
Despite my harsh judgements, though, the first episode was actually pretty good and I'd have to say that the series bares watching. Or, in other words: YAY!! THEY FINIALLY MADE A CARTOON ABOUT THE JLA!!! AND IT'S NOT "SUPERFRIENDS"!!!