I thought it was cool, but dull. The symbolism was very on the nose too, all their money comes from a drug deal and it's stuffed inside a tank full of gasoline painted like the American flag which eventually blows up...
Nicholson's the obvious highlight, both in terms of his performance and his character. He's got one foot in the old world, one in the new. The fact he's the one who gets beaten to death by the locals is interesting. They seem to single him out for some reason despite his being a southerner and the least hippyish of the three. Maybe it was just a case of him not being as essential to the story, so he was the one to go.
One thing which bothered me was the contention that the rural people were threatened by how free they were. I don't necessarily doubt that, but I wasn't sold on them just shooting people for having long hair or whatever. It felt like they conjured an enemy for the sake of the story.