yes, I watch it with my two boys - they're 18 & 16. I think it is very funny. It's not for everyone and I'm sure many people feel it crosses the line...at least once during every episode. Some/most of the characters are over the top.
Yes, Stewie is funny. I love Meg. She is the only semi normal charter in the bunch. I also think Bryan the dog and his crush on Lois is hilarious - he's so charming & everything Peter isn't. Gotta love it.
I'm a fan of Family Guy, but one thing I don't like is how I feel like my IQ level goes down a few points after watching an episode. It's one of those shows that makes fun of everyone of every race, religion, orientation, etc. but for some reason I don't find it nearly as repulsively vile as South Park, which IMO is a horrible show.