Crap Marvel comic adaptations are a genre unto themselves: case in point...the original version of The Fantastic Four, possibly the worst film in history.
The most depressing thing about the JLA movie was that the makers had never seen the excellent Flash tv series which showed how to do it right.
DC characters don't seem to have the same attraction for inept film-makers as Marvel who also have several rubbish versions of Captain America, Doctor Strange, Spider-Man and X-Men (not Bryan Singer's, obviously) to their credit.