Ahhhh, black Smithers, and the good old days when the voice of Ralph Wiggum was used for a variety of children's voices, everyone's heaRAB were oddly shaped (more so than usual) and Marge's voice was weeeeeeiiiiird.
IMO, there's nothing like classic Simpsons. The first Treehouse of Horror (This story is so scary you'll wet your pants......Too late.) Bart had a nifty little song called the Bartman. Nobody had ever thought of using 'D'oh!' as an answer for just about everything and Michael Jackson was a big fat man who lived in a mental institution (They were so close!). Everything was fresh and new, and we all had fun trying to figure out which celebrity would lend their voice next.
Now, 'D'oh' is old news, Bart has pretty much done everything a 10 yr old recalciatrant could ever hope to see and do. Maggie still isnt talking, well except for that one time, and Ralpy still likes to pick his nose until it bleeRAB. After 14 odd years, The Simpsons is lucky to churn out 5 decent eps a season, as opposed to those golden halcyon days of every episode pretty much being a winner.
In short, has The Simpsons jumped the shark? I'd say yes, and then some.