I just reviewed Downton Abbey, Season One at my companion site, 1000 Dvds to See. I gave it one of just 40 perfect 10's I've awarded out of 830 reviews so far. As far as tv goes, and especially Masterpiece Theater, it doesn't get any better than this.
Season one was seven episodes, just under seven hours long. It's the complex story of the lives of both the family members and their staff of servants at a British Manor house, circa 1910, in the waning years of the wealth and power of this class system, when over 50% of the land in England was owned by just 100 families.
I've included some history in my review as well to set the stage for the story, excellently written by Julian Fellowes, who has received 7 of the 12 awards that the mini-series has won to date. Click here for my review
Given it's fans' rating of 9.0 at IMDB, if it were a feature-length film it would be tied for 2nd with The Godfather (1972), only bettered by the 9.1 garnered by The Shawshank Redemption (1994)
Note: I would have just copied the review to this site as well, but Google with lock out a site for 3 days for "duplicate postings"; that happened the only time I did that