Well I doubt it's near the quality of an engineered, titanium prosthetic. But it's a start, and if the plans are open source, other designers could improve them, on their own time, for free, out of the kindness of their hearts.
Over time, we could even see ABS plastic prosthetics with the same level of engineering as the $100k versions, and maybe by then we'll even see cheaper 3D metal printers and home built CNC machines. It could change everything.
Of course, it'd be nice if we could stop seeing poor people in poor countries not losing limbs due to bombs, landmines, military strikes and predator drones.