that is true sharingan can't copy bloodline limits or moves that one to work, like demonic ice mirrors, garra sand sheild or shino bugs or moves that require speical training like regansen or summoning moves(cuase you got to make a pact with the summon first)

sharingan is not unstopable but it seem the best pick of a blood line limit so far at anyrate, lest in my option anyway. i could never get used to see 360 the white-eyes i would get such a huge headache form it lol.