Yes, all or nothing.

Resistance does go lower as temperature drops, but when you hit the transition temperature it suddenly drops to zero.

There are other unusual things that happen too, and only with superconductors.

One of the main ones is that Meissner effect they talked about - that's the exclusion of magnetic fields from inside the superconductor, and regular conductors don't do that.

It sounds like you're asking asking whether some regions of a sample could be superconducting while others are normal phase. This can occur in heterogeneous materials as in a Josephson's junction. Pretty cool stuff when you look at it. An unknown 23 yr old grad student faced down a two-time Nobel prize winner and was right!

Wouldnt that be just "conductive" ? For the usual metals resistance does go down with temperature, but they wouldnt hit zero at zero K.

p.s. I am aware that the article talks about O C and not 0 K.

Superconductivity is phase transition. If I remember correctly first order phase transition. You have it or you not.