I have this bag and love it. It easily fits on my shoulder, though I don't have the exact measurements of the drop length. It is similar to the straps on the cabas piano....
The vertical and horizonal Batignolles are made to be worn on the shoulder, unlike the "standard" batignolles. I think it's the most gorgous mono LV totes! (sorry cabas, Luco, Babylone, and Vavin: I can't love you all equally)