JLU: Season 1 was definitely the high-point of the "Justice League" shows so far. The first disc or so was pretty lame, too much focus on C-list characters I really don't care about in the slightest (Booster Gold gets a whole episode and Flash barely even appears in the first two discs? Please.) There were some gems in there, though, like the Superman's birthday episode.
But once the whole Cadmus deal picks up and the interesting characters finally return to the fold, it easily trumps the weak previous seasons. The animation was definitely a notch above the previous seasons, as well - much more fluid.
And yeah, what in the hell is up with that theme song?
It *might* have worked if the show was made in the 1980s...