Shin was a former test subject of Orochimaru and, even more interestingly, is not a member of the Uchiha clan.
Orochimaru gave him a Sharingan, adding to Shin's Uchiha obsession. Shin eventually tries to experiment on his own and creates a clone army of smaller Shins.
With grand intentions, Shin tries to abduct Sarada Uchiha with his clones.
Though a fascinating and terrifying combination, Shin's weakness lies in his pride. He assumed his clones would want to follow him, but the longer they lived, the more they became individuals.
His life was ended by his own creations. While Naruto could have defeated him, he didn't even have to. Shin defeated himself.
