He is OP. But..
He killed them at there weakest time, SLEEP! Caught them by surprise, while him and Tobi slaughtered them silently (i would assume).
His mom and dad didnt even fight back, his dad being the leader of them all.
Now those are the facts about what happened. Next we have:
He didnt have mastery over his new MS abilitys, so no perfect susanoo! (plus susasoon is to big to not cause a rucuss in the village.)
He didnt have the legendary weapons.
He didnt use Ameratsu, otherwise the village would of been burnt or showed signs of the black flames being there)
He cannot one shot tsukyomi every uchiha, anyone who says or thinks tht are retarded! just using 1 and 2 caused problems for him.
He knew everybodys strenghts and weakness. So he knew what to expect.
He is indeed smart, but others are smart aswell or just as smart. The only ppl who thinks he is the smartest are uchiha fanbois.
He can beat minato tho. Overall only blind fanbois overrate him, but he isn't weak. He is one of the best shown so far for sure.