Seriously. I've watch the second and third series through. And I've started watching the fourth.
Okay it's better post Season 10 (or so) Simpsons but that's hardly saying much. There are some funny bits but it's hardly up there with even moderately good old Simpsons episodes where you just couldn't stop laughing like mad.
I don't hate it. Zoidberg's often worth watching an episode for alone but really: it's just not that great.
It's like Discworld novels after Sourcery where he spent too much time worrying about plots rather than just writing really funny stuff, or the second half of any Bill Bryson travelogue.