"How I Met Your Mother" is a well-executed sitcom. However, where Season 1 mostly just cashed in on the (admittedly enjoyable) genre cliches and easy laughs, Season 2 finally puts some substance into the characters, particularly Barney, who spent Season 1 filling the "quirky friend" role. Neil Patrick Harris never slacks in hilarity and yet somehow makes Barney's surprising character revelations seamless and credible. And Barney's episode on "The Price is Right" is endlessly watchable. Although there are some weaker episodes, most notably "Arrivederci, Fiero", the show continues to pull its punches quickly and without retreading old ground (see exhibit "Friends"). It's well-written, well-acted romantic comedy fun...with Barney.
Neil Patrick Harris makes the show. I can't believe how much I have laughed over the "Price is Right" episode and the lily and marshal's marriage episode. I've recommended both seasons to all my friends and coworkers.