Honestly, I thought this would be a more difficult call, but it really isn't. The Simpsons definitely had their moments, but by far most of those were in the past. The movie was actually pretty good, and contained a lot of the charm that it had in earlier seasons. I think the problem is everything that it has done is now done by someone else, and usually better. It has done musical numbers since time immemorial, but those are always off showtunes, and get lamer every time. Phineas and Ferb, which is aimed largely at children, has much better musical numbers than the Simpsons ever did. Family Guy is by far better at random humor, and South Park has far better topical epsiodes than them as well.
While the Simpsons definitely deserves its own laurel wreath for what it began, particularly with animated humor, it's not what it once was.