I've only owned one pair of button fly jeans, and I hated them. I'm guessing that it was just that particular pair that I had, but they would never stay fastened properly, so I ditched them after about 3 weeks for my regular ones with the zipper/button combo. Even with my 2 pairs of black work pants (one with pure button fly, other with zipper and buttons), I find myself wearing the zippered pair twice as often.