Genius commentary, full stop.
Admittedly, it is not for the easily offended, but that does not make it filth, in my opinion.
I find it interesting to try to guess the political outlook of the creators while watching it.
I could be wrong, but I would guess they are basically libertarian conservatives at heart, but the way they expose each and every ideology and opinion, including conservative opinion, to ridicule is quite refreshing, although, as I said, definitely not for the easily offended or those who lack strong stomachs.
South Park is one of the best things on TV in my opinion, it is like the 12 year old kid who spots that the emperor is wearing no clothes but is the only one that dares to say it, and it makes you wonder, who is really the childish one here, those who take offense, or the creators, who are always one step ahead of any pre-conception you might have had of them.
Of course it is juvenile at times, but that is part of the beauty of the beast.