Hard at first, then softens up really nicely. It'll be heavy though so the fabric will fall very differently to regular denim. If I do turnups on mine they turn into straight drainpipes.
In freezing weather you can feel the fabric gets stiffer/more rigid and looks wise I have never really seen 'crisp' fade lines as the fabric never really creases to an edge at all, it just kind of arches so you get larger, fewer and less defined fades.
What is 21oz like to wear? 14oz is heaviest I've tried.