The funniest sitcom on TV
I'm not sure but this just may be the best season so far with several ongoing storylines like the identity of Barney's father, Marshall and Lily's attempt to get pregnant, Marshall's work problems, Ted's relationship with the edgy Zoey (the excellent Jennifer Morrison, and let's not forget Kyle Mclachlan as her husband The Captain), plus standout single episodes 'The Blitz' with Jorge Garcia as The Blitz and 'Oh Honey' with Katy Perry as Oh Honey, both playing it just right, and there's more from Robin Sparkles. What makes it all work though, apart from great writing and great performances, is the way it's structured with flashbacks, often of the same scene but from different viewpoints or what 'really' happened, teasing flashforwards, and brief throwaway scenes which only pay off in later episodes (sometimes in a later season).
There's a reasonable bunch of extras and, unusually but probably not surprising for this show, the deleted scenes are often very good. I don't usually listen to commentaries but I did with 'Bad News' featuring Jason Segel and Alyson Hannigan. It isn't especially interesting but it's fun to hear Hannigan mooning adoringly over her husband Alexis Denisoff in a guest role (they never share a scene). The gag reel is as funny as you'd expect.
How I Met Your Mother isn't just the funniest show currently on TV, it's one of the funniest shows that's ever been on TV and puts things like Friends in the shade. If you've never watched it, take a punt on Season 1 and I'll be surprised if you aren't back, like I was, for the rest.