people who says otherwise are just blind haters,ignore them my friend. The fact is everything increased exponentially,be it power,strength,stragey,etc. I mean what the **** did you expect? part 1 mainly focused on genin battles ffs,whereas in part 2 every ****ing ninja is chunin,jonin,kage or above. And seriously,for a story which began with the nine tails legend of overwhelming power,not to mention that even the fact that he was stopped means that shinobi's of jonin and kage level were always op.
and btw,PART 2>>>>PART 1.