The weird thing is what a strange group of deities they chose (aside from the whole having them kill human sacrifices, which was ludicrous).
Mercury isn't really one of the powerful gods in Roman mythology -- he's the messenger, and kind of a flunkie, which worked for the plot, but an odd choice. Where was Apollo?
But then no one worships those gods anymore, or if they do, they're part of a teeny tiny group of folks somewhere. And then if you're including those, why not a Celtic deity? And as someone (ita?) pointed out, Baron Samedi isn't even a deity, he's a loa.
The episode didn't offend me the way it did most people, I think because on first watch I loved the idea of a sort of theological UN discussing the Judeo-Christians' pesky apocalypse. Even now, I don't know if they were going for metaphor -- maybe like the Christian god, the others don't really care about their followers so much as consider them inferior beings suitable for whatever use is necessary.
I still enjoyed the episode for the Gabriel/Lucifer showdown, and for Sam and Dean being such a team again!, and for a lot of the pop culture references and humor, and because it surprised me in that completely unexpected twist way. And I feel like it could have been so much better if they had thought it through more carefully and actually taken the characters and the setup to a more developed conclusion, but based on the previews for next week, I think we're done with extra-deity intervention.
I'm still really sad about Gabriel, too. ::sniffle::