Too long to handle comfortably. I've never liked it. I do make sure to typeset two versions of things I do so Europeans can have something they're familiar with (and their tooling prefers), but I just prefer things a little shorter and a little fatter.
edit: about A5 specifically, I prefer 5½ x 8½, which tends to become 5¼ x 8¼ (even smaller) after trimming the bleeds.
