Basically, mainly, they're funny. Let us never lose sight of this basic fact.
But, they are also very witty, very well-informed parodies based closely on the actual texts they parody. The Socks are also a wonderful example of the truth that you don't need tons of fancy equipment to be witty, sly, wise . . . to be art. These socks would never have gotten out of their wellies (so to speak) if their creator (Kev Sutherland) hadn't had the confidence to start making campy, witty, well-rehearsed satires with the materials at hand.
Also, if you watch enough of the sublime Socks, you start to notice that they play off one another --- which is remarkable because as I understand it, they are played by one man. But I feel that he must be an extremely talented artist --- you can almost imagine him projecting his characters up his arms.
But mostly they're funny. Enjoy. I'm off to the beach. :)