Yesterday's Dollhouse (1x06) was both the first good and the first EXCELLENT episode of the series -- the first episode that made me feel I was getting two episodes' worth for the price of one, rather than a 10-minute idea stretched to hourly lengths.

5 bad-to-okay episodes followed by an excellent one. Let's see how the 7th one goes.

( Saw Watchmen last Sunday. Minor spoilers )