Justice League Doom is by no means a bad movie. But it does exemplifies what went wrong with the animated DC movies after the end of Justice League Unlimited. Which is, that none of the subsequent animated DC movie offerings were part of the animated DC universe. Long-time comic readers often groan at the amount of continuity their favorite universe has accumulated over time, while forgetting that one of the biggest draws of the universes is the continuity itself. Good stories I can easily get, but good stories in an on-going universe with a decades long history, there aren’t too many of them around.
So what’s the problem with Justice League Doom? Well, the original story by Mark Waid was a sort of culmination of years of continuity build-up, something that succeeded not because it was entirely stand alone, but because it tied into the Justice League history from the (third) inception in Waid’s own A Midsummer’s Nightmare right through the entirety of Morrison’s run on the title and then to Waid’s run again. Sure, it can be read without having read the years of build-up, but if you have it packs a much bigger punch.
And that was my feeling when watching Justice League Doom, that I had missed the years of build-up to transform the movie experience from merely watchable to good or even great. I had similar reactions to Crisis on Two Earths and the animated Superman movies (Doomsday, Public Enemies, Apocalypse and All-Star). If they had tied them into the animated DC universe, tweaked them to fit the continuity that came before, all these movies could have had a much bigger impact and still functioned as self contained stories.