Jeph's always trying to improve his art.
I don't always see his choices as improvements, but that's why it's his art. I wouldn't care much about his opinion of my art, so I'm not overly concerned about his quality at any given moment.
Sometimes Marten still looks kinda creepy, but hey, if I find myself thinking that's somehow not good art, I click the first button.
Jeph got from comic 1 to his best art by constantly challenging himself. Odds are he'll reach a new height, and if the dice fall against the odds, it's not like I'm paying for it.
Actually, come to think of it, I was paying for it but I got my money's worth. The comic delivered what I paid for. Nowhere did it say I had any say in how Jeph did that.