This was a great idea poorly implemented. I find the shape to be a little clumsy but useable. The spread on the fork is also smaller than I would like but the thing that makes this barely useable is the insufficient tension on the floss.
When trying to floss between tight teeth, the lack of sufficient tension allows extra floss to be pulled out leaving it with excessive slack. The narrow space between the forks makes the situation even more cumbersome to the point that after using it only twice, I'll probably throw it out.
This is a real shame because it was a truly brilliant idea unfortunately implemented by a company where I suspect, marketing and accounting hold sway over engineering. If this was made refillable, and the tension issue fixed, it would be a truly green product using a tiny fraction of the floss normally used by hand. But by constantly having to tighten the floss, you end up using just as much floss and taking twice as long as if you'd done it by hand. I also find theie claim of "250 uses" to be rather dubious. I suspect this really means 250 cycles of the floss advance lever which would work out to more like 25 uses for me.