You are all waiting for me to weigh in on this thread so here I go:
Carlin: funny, influential comedian who was among the first to popularize the "you ever notice..." type of humor that was later adopted by Seinfeld, Steven Wright and others. Probably not one of the best comedians ever, but certainly one of the best of his generation.
I saw Carlin live in the mid-70s when I was a teenager. I don't remember much about the performance other than I was taken aback at all of the adults laughing at his coarse language and subject matter. I was kind of sheltered.
There are a lot of people here who rag on Carlin because he wasn't as funny in his later years. Who among us is as good at his profession at the age of 70 than he was at the age of 30? Very few, I would imagine.