I've heard people of my age or near it say that Sesame Street nowadays isn't as good as it was when we were kids, and from the few occasions that I have had to watch Sesame Street with my nephews, I've been inclined to agree. But over the last few days I've watched clips from all throughout the show's history, and some of the more recent ones are really funny, while some of the older ones are odd and unfunny (somehow "James Earl Jones says the alphabet" sounded a lot more interesting than it turned out to be).
I think the difference is this: Sesame Street bits tend to fall along a spectrum, with one extreme being "Educational" and the other extreme being "Art for Art's Sake." In the above clip, I have no idea what Kermit is trying to teach, so that bit is closer to the "Art for Art's Sake" end of the spectrum. I think that nowadays a concerted effort is being made to keep most bits closer to the "Educational" end of the spectrum so, while they vary in entertainment value, you can usually tell what educational purpose the bit is trying to serve. Which, I suppose, is just as well; it wouldn't do for Sesame Street to lose its educational credibility.
Another noticeable (and sometimes annoying) difference, especially to people my age and older, is the Elmo-centricity of the show. Elmo is not my favorite character on the show because, by the time he rose to prominence, I had stopped watching the show regularly (not because I wanted to, but because I had to go to school). However, Kevin Clash is a mensch, so I no longer mind Elmo being the face of Sesame Street. But of all the Muppets, Sesame Street and otherwise, Kermit is my favorite, possibly because he belongs to both Muppet "families"; possibly because he's just so inherently lovable.
In any case, older clips like this in which Jim Henson is voicing Kermit really, really get to me.
UPDATE: By the way, I've been doing some research and apparently this song is called "If I Were" and originates circa 1981-1982, so it's entirely possible that I saw it before and just don't remember it on a conscious level. Apparently some people also know it as "Sonnet," which makes sense inasmuch as a sonnet is mentioned, but on a literal level makes no sense because it is not a sonnet (it's in trochaic hexameter, for one thing). They might just as well call it "Bunny" or "Cruller."