Most important to me are the proportions, and if they present a balanced, harmonious pipe, and what can unbalance a pipe for me is many a splendored thing. To my eye, Bill Taylor couldn't turn out a balanced bulldog, something about the transition from the shank to the bottom of the bowl on his irks me. While I love smoking Charatans, a lot of their proportions are jarring to my eye. Comoy's shaping usually hits exactly right.
Now, we have a thing of beauty. If I smoke it and it smokes like a turd, it's still beautiful, but I won't keep it. Function is king, and beauty is not enough reason for it to stay. Sorta like getting a '68 Chevelle SS and finding out some joker put a Honda Accord engine in it.