Well for what we know right now, she is herself and not a puppet.
I disagree. If they show how logical and powerful that they are and if they impress me and put on a show, then they are a great villain.
Even taking time to taunt can give the enemies openings. Those who spend time taunting usually end up regretting it. Besides, she already did say in the beginning "I will finish you here and now". That is a taunt.
Then the tension came right back when Naruto and Sasuke got separated. There is nothing wrong with a little humor.