Yes, the nitinol is not the only component. You would need things to mimic other pieces of the system, like tendons and a way to anchor them to false structures or utilize existing bone.

I mentioned fitting similar to spandex because all these other suits are bulky. Sure, this system would still have bulk, but it should be more conforming than mechanical legs that sit several inches outside of the person's natural legs. Good luck fitting on public transportation, airplanes, or even walking through a 32" door if you were a bigger person to start with.