Initially I found the stem shifters on my Motobecane difficult to use for all the reasons described by Weasel9, plus the fact that they were quite stiff and difficult for me to move. However, now I have gotten quite accustomed to them and enjoy the feeling of using them. Still, if I were putting a bike together from scratch, I would go with bar-ends because of the danger of impaling yourself on stem shifters during a fall.