Humor's a sensitive subject because it's subjective and what you find funny I might not find funny. That being said, a good joke has form and content, and CAD can be criticized on form. Yahtzee, in some interview or another, made this point by comparing CAD's and PA's strips about puzzle quest: Penny Arcade's is a classic "beat, beat, punch" format, while CAD front-loads the entire premise then sort of withers. Pointing this out is constructive criticism: in this case mr. buckley's eye for a good joke was right on, but his execution needed work. He's got a good joke with wider appeal if he just re-arranges things.
Buckley's success proves his sense of humor resonates but that doesn't mean he's beyond criticism. And he has earned a reputation for dismissing or lashing out against detractors. It may be he's changed, in which case given time he'll stop reaping the karmic rewards for past drama. Admittedly writing CAD must be harder than writing PA: he's flying solo (and anyone who's listened to the PA podcasts can tell you how quick ideas seem to come together with two maniacs working together), and he's got continuity to worry about which means he has to handle every corner he writes himself into on-the-fly.
I like quite a few webcomics. I never miss a PA, a Schlock Mercenary, an XKCD, or a YAFGC. That said, I'm not afraid to say so when PA is waning in teh funny department. Sometimes it gets into a real slump. I feel like they were in a mild one recently until the ping pong thing started. But if you're an RPG geek and you don't like "The Skills," http://www.penny-arcade.com/comic/2004/12/10/ then it's fair to say I don't understand your sense of humor.
