I don't find it offensive, but then I like Bill Hick's, Frankie Boyle, Billy Connolly All of whom have been described as offensive at one time or another.
Stewie/Brian driven stories are always entertaining to watch, but the other characters are are so one dimensional that it has been very evident in the current series that the writers are struggling to find even adequate plotlines for them to explore and as a result are just resorting to gross abuse to fill the shows.
Meh. Seth McFarlene has been purposely pushing his boundaries since the show started. That's its selling point, sort of like with South Park. It's very wrong and highly offensive, which is why people love it. As long as some people keep reacting to it, it'll keep being offensive and other people will keep watching it.
I, personally, don't get offended by any of it. It's not really serious. It's too stupid to be offended by. As I said, Seth McFarlene just likes to toe the line and see how far he can take things. I do enjoy most of the show, but recently I think he's just been trying too hard to piss people off and it just isn't funny anymore. Just annoying.
Not offensive to me personally, no. But I can see how it offends other people. Seth Green hahahah! But that's what makes it one of the best shows there is. It's not afraid to make people feel outraged. Making people feel something is what gives all stories impact