The first 2 seasons are good - 4/5 stars. The next 4 are drawn out and repetitive. The dream sequence episodes are the best episodes of the show, there's a lot of padding and weak characters created to push plots and subplots forward in the 3rd through 6 seasons. The theme of decline and change in America is better integrated in the first 2 seasons, when it is  quiet, all subtexts and interpersonal character tensions become too loud and over-worked in the last few seasons.