I think that Dark Side is musically perfect, in that you change one note or effect and the overall album would be lessened, but I don't tend to listen to it as often as the others. Don't know how many times I have bought a cooy of Dark Side though over the years. Vinyl when it came out, cassette...
Will be worth checking out. I know purists love the earlier stuff, but I adore Monetary Lapse of Reason and Division Bell. Probably the band I most turn to when I want something on the iPod.