First of all, ignore the comment about how South Park should make fun of Republicans. Everyone is doing that now, why should South Park blindly follow what the rest of the media is doing? And what the Republicans are doing is more serious and less funny than Al Gore and his global warming hysteria.
But all that aside, this episode is just plain funny. Al Gore's portrayal has to be one of the best caricatures of a politician I've ever seen, it was original, and it was based on peoples opinions of the man. I don't want to give anything away, but it had me rolling on the floor.
There are also has some of the best Cartman/Kyle moments ever.
All in all I'd say that this is one of the best episodes the show has ever had, and I would highly recommend it to anybody.