Starting with a substantive flashback on the eve of Camelot's fall, and a revised origin for Jason Blood/the Demon, this episode doesn't slow down for much of anything. Batman and Jason Blood join forces and from there the Justice League become smoothly integrated into the episode. The Demon is...well, a Demon, and his interplay with the team members is interesting - even Batman seems to defer to him. This ain't the Superfriends anymore.
The Mordred/Morgaine interplay is amusing, although Morgaine's powers never really get defined. Still, she's a formidable threat for the League members assembled. Best characterization overall: J'onn J'onzz, who gets some welcome backstory on his Martian origins, and Wonder Woman, who thankfully becomes a bit more mature.
Overall, a excellent entry into the show - one of the best of the series.