Attentive fans will be rewarded with a wealth of small references to past episodes. Though there are moments when the fundamental premise--that this is all part of an unbearably long story that a future Ted is telling to his children--feels obnoxiously stretched (toward the end of the season, one episode in particular builds up to a false revelation), for the most part HIMYM is a sterling example of a well-sustained sitcom; the characters have successfully grown over the four seasons without losing everything that made them funny in the first place. The number of extras is surprisingly small--only a few show commentaries, an enjoyable group interview, and an extended version of Barney's video resume. --Bret Fetzer

Stills from How I Met Your Mother: Season Four (Click for larger image)