I really, really like the new Gideon. In this new Aggro environment, he will fit GREAT, and just ramp up loyalty like a madman. His 0 ability was pretty much a given, joining the fray himself is kinda his thing.
His Ultimate does give the "last resort" sorta feel. "I won't make it, but neither will you!" white cards always appealed to me, stuff like Planar Cleansing (and similar cards in other colors, like Worldfire, too) and it can set up a great FINAL TURN~ kinda deal. Tap out all your lands, use his ultimate, unleash a torrent of haste wielding weenies, Battallion for game.
I'm assuming this is what his ultimate was meant to synergy with. I mean, he's gotta ba paired with Boros for SOME reason.
(Funny thing is, Gideon learned all of his tricks from a Hieromancing Planeswalker. Hieromancers are Law mages. One would expect Gideon would sooner join Azorius)