Susanoo isn't manifested by Yin Release. It's manifested by Chakra. What makes it durable is the fact it's more of an emphasis for defence and less of an offense. PS is able to defend from mountain range attacks, but its attack power is only cutting a mountain. Susanoo is an inspiration from the myth.
But Susanoo still has a weakness, as with any other Jutsu. A Susanoo manifested only from the upper body, meaning it has no legs is weak from underneath attacks. Obviously it's got no legs, so it's vulnerable when you attack it from below. This was shown with Gaara pulling Madara from his Susanoo, and Kabuto destroys Sasuke's ribcage Susanoo via Suiton. Attacks from underneath are leg-less Susanoo's weakness.
A legged Susanoo nullifies its previous weakness, but it's still prone to raw power or hax techniques, which either destroy Susanoo entirely or affect the user. Jinton atomized it before showing its made of molecules; Banshon Ten'n can pull the user; Gakido can absorb it etc.
