Yes it is still relevant,
The show has changed and evolved over the years, especially with shock value shows like south park and family guy on the air. The Simpsons doesnt have the mockery of popular culture like South Park, nor the strength of story, and it doesnt have the high joke output of Family Guy.
What I have noticed is that the Simpsons now plays a more emotional role with it's characters, trying to get us to identify with them more.
The story commonly revolves around secondary characters like Moe or Mr. Burns as oposed to shows like Family Guy where that doesnt happen.
The Simpsons have always been the best at doing shows that parody movies, books, and american history, looking for these sometimes subtle references is always fun.
The shows this year in my opinion have been pretty decent. I especially liked the one where Bart and Ralph and the other bad kids go on a field trip with Principal Skinner, and the one where Mr. Burns starts his own Basketball team.
The visual humor has also come more to the forefront in the show, with lots of funny songs and colorful fantasies.
So yes it is still relevant and funny.