I just don't get all the Atrocitus love. With his own series, a role in the Abin Sur tale in Green Lantern: Emerald Knights, and now the main foil in this show, he certainly has taken center stage. However, for me, he doesn't work as a villain. In the comics, he is more sympathetic than Sinestro, at least to me, what with the destruction of his entire sector, and I would much rather seen Quill in GL: EK than Atrocitus (with the Mogo story being as true to Alan Moore's work as possible, I don't understand why they didn't just animate "Tygers").
And for a TV show ostensibly aimed at kids, Atrocitus and the Red Lanterns are an odd choice. I guess they didn't want to go with the logical choice in Sinestro in case there's a sequel, but that would have made more sense (since Sinestro was a Lantern and yellow/fear is the main weakness of GLs). I'll wait to see how it's handled and it certainly does not diminish my excitement for the show, but I am a bit disappointed in that choice.